Display panel and manufacturing method for the same including improved bonding agent application method

ABSTRACT

Barrier ribs  18  formed on a back substrate PA 2  are brought into contact with a bonding paste layer  40  having an even surface, applying a bonding agent Bd evenly to the tops of the barrier ribs.  
     Furthermore, a gas discharge panel having a structure in which discharge mainly occurs at locations distanced from parts of the panel connected using the bonding agent Bd is realized.

TECHNICAL FIELD

[0001] The present invention relates to a method for manufacturing adisplay panel constructed from a pair of connected substrates, and inparticular to a method for applying a bonding agent to the substrates.

BACKGROUND ART

[0002] An AC-type plasma display panel (hereafter abbreviated to PDP) isa type of gas discharge panel, well-known in the art as one example of adisplay panel.

[0003] A PDP is illustrated in FIG. 42. Here, the PDP is constructedfrom a front substrate 2000 and a back substrate 2100. The frontsubstrate 2000 is generally produced by forming discharge electrodes2002 upon a front glass plate 2101. This structure is then covered witha dielectric glass layer 2003 and a protective layer of magnesium oxide(MgO) 2004.

[0004] The back substrate 2100 is formed by arranging address electrodes2102, barrier ribs 2103 and a phosphor layer 2104 on a back glass plate2101. The front substrate 2000 and the back substrate 2001 are thenfixed together, and discharge spaces 2200 are formed by introducing adischarge gas into the spaces demarcated by the barrier ribs 2103. Cellsare formed in the discharge spaces 2200 at the points where dischargeelectrodes 2002 and address electrodes 2102 intersect. FIG. 42 showsonly one such cell, but in fact the PDP normally includes a plurality ofcells in which the phosphor layer 2104 is composed of alternating red,green and blue phosphors, enabling a color display to be produced. Notethat in the drawing, the discharge electrodes 2002 and the addresselectrodes 2102 are drawn as if arranged in parallel, but in fact theyare arranged at right angles.

[0005] A discharge gas, such as a mixture of neon and xenon, is normallyenclosed into the discharge spaces 2200 at a pressure of around 500torr.

[0006] In practice, however, such conventional PDPs have not always beenable to achieve satisfactory luminance. In order to improve luminance,it is considered necessary to enclose the discharge gas inside thedischarge spaces 2200 at an internal pressure exceeding 500 torr.

[0007] However, when the internal pressure in the discharge spaces 2200is raised to 760 torr or 1000 torr, for example, gaps are generatedbetween the barrier ribs 2103 formed on the back glass plate 2101 andthe front substrate 2000, while the front and back substrates 2000 and2100 bulge outwards. This means that neighboring discharge spaces 2200are no longer effectively divided by the barrier ribs 2103, causing thedisplay performance of the PDP to deteriorate.

[0008] Even if the internal pressure is set at 760 torr or less, thebarrier ribs 2103 are not connected to the front substrate 2100, so thatexternal vibrations or vibrations caused by driving the PDP itself.bring the barrier ribs 2103 and the front substrate 2000 repeatedly intocontact, generating noise.

[0009] In order to correct these problems, one related technique hasproposed that the topmost edge of the barrier ribs 2103 be coated with abonding agent before fixing the pair of substrates together to form thedischarge spaces 2200. A gas discharge panel in which gas has beensealed at a higher pressure is produced, realizing an improvement inluminance. Such a procedure is described in Japanese Patent ApplicationNo. 9-49006.

[0010] However, when a well-known method such as screen-printing is usedto apply the bonding agent to the topmost edge of the barrier ribs 2103,it is difficult to apply the bonding agent equally to the very long andnarrow top surfaces of the barrier ribs 2103 without leaving some partsuncovered. In the case of screen-printing, matching an aperture patternaccurately to the shape of the barrier ribs 2103 has proved extremelydifficult. As a result, finding a simple method for improving bondingstrength, while maintaining display performance and preventing thegeneration of distortion when the barrier ribs 2103 touch the frontsubstrate 2000 has posed considerable obstacles.

[0011] Furthermore, the properties of the dielectric glass layer 2003covering the electrodes change if exposed to the discharge spaces 2200.As a result, a protective coat of MgO or similar is usually formed tocover the surface of the dielectric glass layer 2003, as describedabove. Even if a protective layer 2004 is applied in this way, however,the tops of the barrier ribs 2103 are connected after the protectivelayer 2004 has been applied, and so the surfaces of the bonding agentare not covered by the protective layer 2004. Thus, the properties ofthe surface of the bonding agent change as a result of exposure to thedischarge spaces 2200. Substances produced by this change pollute thedischarge spaces 2200 and are the cause of such problems as rises indischarge voltage, falls in discharge efficiency and deterioration inthe phosphors.

DISCLOSURE OF THE INVENTION

[0012] The present invention has been developed in view of the aboveproblems in the background art. A first object of the invention is toprovide a display panel manufacturing method performed by connecting twosubstrates together as strongly as possible using a bonding agent, andin particular to provide a simple bonding agent application method forarranging the bonding agent evenly on the narrow areas that form thetops of the barrier ribs leaving almost no uncovered areas.

[0013] A second object of the present invention is to provide a gasdischarge display panel capable of preventing changes in the propertiesof the bonding agent surface caused by discharge.

[0014] To fulfil the above first object, a display panel manufacturingmethod, comprising an application process for applying a bonding agentto a plurality of barrier ribs formed on at least one of a. pair ofsubstrates, and a connection process for arranging the pair ofsubstrates in opposition and connecting the pair of substrates togethervia the bonding agent that has been applied to the barrier ribs isprovided. The application process includes a bonding agent holdingprocess for having a bond holding member hold a paste-like bond to forma surface; and a bonding agent applying process for applying the bondingagent to almost an entire top surface of each barrier rib by bringingvirtually the entire top surface of each barrier rib into contact withthe bonding agent layer, while regulating a degree of contact betweenthe bonding agent layer and the barrier ribs.

[0015] In this invention, barrier rib tops and the bonding agentarranged on the barrier rib tops are aligned using surface tensioncreated on the surface of the barrier ribs by bringing the barrier ribtops and the surface of a bonding paste layer into the appropriatedegree of contact. This method is used rather than a screen plate withan aperture pattern like that used in screen-printing. As a result, thebonding agent can be applied evenly along the narrow barrier rib topsusing a simple technique, even if the barrier rib tops are not strictlylinear, and form wavy lines.

[0016] This means that, if a screen-printing method is used when thebarrier ribs are arranged in a stripe formation, aligning the barrierribs with the screen plate is difficult due to slight variations inbarrier rib pitch. As a result, when such a conventional technique isused, the barrier rib tops and the bonding agent are not correctlyaligned, and the bonding agent cannot be evenly applied to the barrierrib tops. Furthermore, if the barrier ribs are formed in wavy lines,aligning the barrier ribs accurately with the screen plate is moredifficult, and applying the bonding agent evenly to the barrier rib topsbecomes even more problematic. In contrast, using the present inventionenables the bonding agent to be applied evenly to the barrier rib topswithout the variations in barrier rib pitch and barrier ribs formed inwavy lines having any impact.

[0017] Here, the bonding agent can be applied more liberally to thebarrier rib tops for connecting with the front substrate than waspossible when it could not be evenly applied, producing a display panelwith greater bonding strength.

[0018] By attaching the bonding agent to the barrier ribs using surfacetension as explained above, the bonding agent can be applied to thebarrier rib tops in an ideal shape. This reduces the degree of bondseepage into the cell area, so that the fall in the amount of luminanceproduced from the front glass plate is limited.

[0019] The following is an explanation of the ideal shape in which thebonding agent should be applied to the barrier rib tops. FIG. 41 shows across-section of this shape.

[0020] As shown in FIG. 41A, the ideal shape for applying the bondingagent 2300 is formed so that the bonding agent 2300 is more thicklyapplied near the center of the barrier rib top as seen in cross-section,and becomes thinner towards the edges. When the barrier ribs 2103 areconnected to the front panel, the bonding agent 2300 oozes out fromeither side of each barrier rib 2103, as shown by the protruding parts2301 in the drawing. Such protruding parts 2301 reduce thelight-emitting area as seen from the front glass plate by acorresponding amount, causing luminance to deteriorate. Accordingly, theprotruding parts 2301 need to be made as small as possible to limitdeterioration in luminance. Thus it is preferable for the shape of thebonding agent 2300 before the barrier ribs are connected to be formed sothat a thinner coating runs along both sides of the top of each barrierrib 2103.

[0021] Here, the bonding agent applying process includes a first stepfor arranging the substrate on which the barrier ribs are formed and thebonding agent in opposition, with a gap between the barrier rib tops andthe bonding agent; and a second step for regulating the degree ofcontact between the barrier rib tops and the bonding agent bycontrolling the distance between the barrier ribs and the bonding agent.

[0022] This enables the distance between the bonding agent and thebarrier rib tops to be appropriately regulated, allowing the amount ofbonding agent attached to the barrier rib tops to be easily controlled.

[0023] Here, the bonding agent applying process includes a third stepfor placing the substrate on which the barrier ribs are formed and thebonding agent in opposition, with a gap between the barrier rib tops andthe bonding agent; a fourth step for bringing one part of each barrierrib into contact with the bonding agent by controlling the distancebetween the barrier ribs and the bonding agent to a distance at whichthe bonding agent is applied to the barrier rib tops as a result ofsurface tension; and a fifth step for bringing the surface of thebonding agent and virtually the entire surface of each barrier rib topinto contact by altering the relative positions of the bonding agent andthe barrier ribs while maintaining the distance between the barrier ribsand the bonding agent to a distance at which the bonding agent continuesto be applied to the barrier ribs as a result of continuing surfacetension.

[0024] This enables the distance between the bonding agent and thebarrier rib tops to be appropriately regulated, allowing the amount ofbonding agent attached to the barrier rib tops to be easily controlled.

[0025] Here, the bonding agent applying process further includes a sixthstep for placing the substrate on which the barrier ribs are formed, andthe bonding agent in opposition, with a gap between the barrier rib topsand the bonding agent; and a seventh step for bringing the barrier ribsinto contact with the bonding agent using a regulating means forregulating the position of the barrier rib tops in relation to thebonding agent.

[0026] The bonding agent is applied to the barrier rib tops by bringingthe barrier rib tops into contact with a regulating device forregulating the position at which the barrier rib tops touch the bondingagent. This enables the degree of contact between the bonding agent andthe barrier rib tops to be easily regulated, allowing the amount ofbonding agent applied to the barrier rib tops to be simply controlled.

[0027] Here, the bonding agent applying process further includes aneighth step for altering the relative positions of the bonding agent andthe barrier ribs with the barrier rib tops in contact with theregulating means.

[0028] This enables the bonding agent to be attached to the barrier ribtops without any irregularities.

[0029] Here, the bonding agent holding member is a rotating object onwhose surface the bonding agent is held; and the bonding agent applyingprocess includes a ninth step for bringing the bonding agent intocontact with virtually the entire surface of the barrier rib tops byrotating the bonding agent holding member to move the point of contactbetween the bonding agent and the barrier rib tops along the length ofthe barrier ribs.

[0030] When the panel is mass-produced, this enables the bonding agentto be applied efficiently to the barrier rib tops, without halting themovement of the production line.

[0031] The bonding agent applying process should preferably be repeateda plurality of times.

[0032] The bonding agent is held by a regulating means. This enables thedegree of contact between the bonding agent and the barrier rib tops tobe more appropriately controlled.

[0033] The bonding agent may be formed in a layer on the top of a flatplate.

[0034] The regulating means may be made from wire rods, which are eitherinterwoven or lined up precisely. The regulating means may also becomposed of indentations and protrusions formed on the surface of thebonding agent holding member.

[0035] If the bonding agent is applied after implementation of a processfor leveling the barrier ribs across the entire surface of the substrateso that all the barrier rib tops are at approximately the same height,variations in the amount of bonding agent applied, caused by variationsin the height of different barrier ribs or along the length of onebarrier rib, are eliminated. This allows the bonding agent to be evenlyapplied to the barrier rib tops without any irregularities.

[0036] In order to achieve the first object, a display panelmanufacturing method, for connecting a pair of substrates arranged inopposition via a plurality of barrier ribs formed in a specific patternon at least one of the substrates and a bonding agent arranged on thebarrier ribs is provided. The display panel manufacturing methodincludes a barrier rib pattern forming process and a bonding agentpattern forming process. These processes include a first step forlaminating the bonding agent and a material for forming the barrier ribsby forming layers of certain thicknesses; a second step forsimultaneously removing corresponding parts of the laminated barrier ribmaterial and bonding agent to form the specific pattern; and a thirdstep for transferring the pattern formed in the barrier rib formingmaterial and bonding agent to the substrate on which the barrier ribsare to be formed.

[0037] Here, the barrier rib tops and the bonding agent arranged on thebarrier rib tops are aligned by removing corresponding parts of thebarrier rib and bonding agent layers at the same time. The pattern forthe barrier ribs and the bonding agent can thus be formedsimultaneously. This method is used rather than a screen plate with anaperture pattern like that used in screen-printing. As a result, thebonding agent can be applied evenly along the narrow barrier rib topsusing a simple technique, even if the barrier rib tops are not strictlylinear, and form wavy lines. This produces a display panel with greaterbonding strength.

[0038] Also in order to achieve the above first object, a display panelmanufacturing method, for connecting a pair of substrates arranged inopposition, via a bonding agent, which has been applied to a pluralityof barrier ribs formed in a specific pattern on at least one of thesubstrates is provided. The display panel manufacturing method includesa barrier rib pattern forming process for forming a barrier rib patternby pressing a first pattern-forming member onto the barrier rib formingmaterial, the barrier rib forming material being of a set thickness, anda bonding agent pattern forming process using a pattern-forming memberhaving the same pattern as the pattern-forming member used in thebarrier rib pattern forming process.

[0039] Here, the barrier rib tops and the bonding agent arranged on thebarrier tops are brought into contact by using a pattern forming memberwith the same pattern to form the pattern for the barrier ribs and thebonding agent. This method is used rather than a screen plate with anaperture pattern like that used in screen-printing. As a result, thebonding agent can be applied evenly along the narrow barrier rib topsusing a simple technique, even if the barrier rib tops are not strictlylinear, and form wavy lines. This produces a display panel with greaterbonding strength.

[0040] Here, the barrier rib pattern forming process and the bondingagent pattern forming process include a first step for laminating thebarrier rib forming material and the bonding agent by forming layers ofcertain thicknesses; a second step for simultaneously pressing down thelaminated barrier rib forming material and bonding agent using a samepattern-forming member to form the specific pattern; and a third stepfor transferring a molded pattern formed in the barrier rib formingmaterial and bonding agent to the substrate on which the barrier ribsare to be formed.

[0041] This enables the pattern of the barrier ribs and the bondingagent to be formed simultaneously using the same pattern-forming memberhaving the same pattern for forming the barrier ribs and the bondingagent. The barrier rib tops and the bonding agent can thus be moreaccurately aligned than when the method was restricted only to using thesame pattern to form the barrier ribs and the bonding agent. Inaddition, the bonding agent can be applied evenly along the narrowbarrier rib tops using a simple technique, even if the barrier rib topsare not strictly linear, and form wavy lines. This produces a displaypanel with greater bonding strength.

[0042] Here, at least one indentation and protrusion is formed on theparts of the pattern-forming member that correspond to top surfaces ofthe barrier ribs on which the bonding agent is applied.

[0043] Here, the alignment of the barrier ribs and the bonding agent isdetermined by indentations and protrusions, allowing the bonding agentto be arranged more accurately on the barrier rib tops. This produces adisplay panel with greater bonding strength.

[0044] Also, in order to achieve the above first object, a display panelmanufacturing method, for connecting a pair of substrates arranged inopposition via a bonding agent arranged on a plurality of barrier ribsformed in a specific pattern on at least one of the substrates isprovided. The display panel manufacturing method includes an indentationforming process for forming at least one indentation on a top of eachbarrier rib; and a bonding agent arranging process for arranging thebonding agent in the indentations.

[0045] The barrier rib tops and the bonding agent arranged on thebarrier rib tops are here aligned by indentations formed in advance inthe barrier rib tops. This method is used rather than a screen platewith an aperture pattern like that used in screen-printing. As a result,the bonding agent can be applied evenly along the narrow barrier ribtops using a simple technique, even if the barrier rib tops are notstrictly linear, and form wavy lines.

[0046] When the bonding agent is arranged on barrier rib tops withoutindentations, the bonding agent tends to seep off the barrier rib tops.This is another reason why the bonding agent cannot be arranged evenlyon the barrier rib tops. Since the bonding agent in the presentinvention is arranged in the indentations formed in the barrier ribtops, this kind of run-off is prevented, enabling the bonding agent tobe applied evenly to the barrier rib tops. As a result, a display panelhaving greater bonding strength can be obtained.

[0047] Additionally, arranging the bonding agent in the indentationsprevents the bonding agent from trickling down from the barrier rib topsinto the front glass plate side of the panel when firing is performed.

[0048] The barrier rib pattern is formed by pressing a pattern-formingmember onto the barrier rib forming material, the barrier rib formingmaterial being arranged in a layer of a specific thickness, and theindentation forming process is performed simultaneously with the barrierrib pattern formation when the pattern-forming member is pressed ontothe barrier rib forming material.

[0049] Here, the bonding agent may be arranged in the indentations usinga screen-printing method, or by a method in which the bonding agent isinjected into the indentations via a nozzle. Of the several possiblemethods, the nozzle-injection method is preferred since this methodapplies the bonding agent to the indentations most accurately.

[0050] In order to achieve the first object, a display panelmanufacturing method, for connecting a pair of substrates arranged inopposition via a bonding agent arranged on a plurality of barrier ribsformed in a specific pattern on at least one of the substrates isprovided. A process for arranging the bonding agent on the barrier ribsincludes an attaching process for attaching a first member to thebarrier ribs; a first removing process for forming holes in the firstmember at positions corresponding to tops of the barrier ribs; a bondingagent filling process for filling the holes in the first member with thebonding agent; and a second removing process for removing the remainingfirst member.

[0051] Here the barrier rib tops and the bonding agent arranged on thebarrier rib tops are aligned based on a pattern formed so that itconforms to the barrier rib pattern. This method is used rather than ascreen plate with an aperture pattern like that used in conventionalscreen-printing techniques. As a result, the bonding agent can beapplied evenly along the narrow barrier rib tops using a simpletechnique, even if the barrier rib tops are not strictly linear, andform wavy lines. This enables a display panel with greater bondingstrength to be obtained. Furthermore, the bonding agent is preventedfrom flowing off the barrier rib tops by the first member, until thefirst member is removed.

[0052] The adhesion process is performed by applying the first member tothe barrier ribs after a connecting layer is formed on either thebarrier ribs or the first member.

[0053] The first removing process forms holes by irradiating the surfaceof the first member with a laser.

[0054] The laser irradiation is controlled according to measurementstaken to locate the barrier ribs. This enables the parts of the firstmember adhering to the barrier rib tops to be removed accurately.

[0055] Here, it is preferable that a material used for the barrier ribtops absorbs laser light more easily than a material used for otherparts of the barrier ribs.

[0056] A photoresist may be used as the first member; and the firstremoving process form holes by irradiating the first member in aspecific pattern and then developing the first member.

[0057] The first removing process may form holes in the first memberadhering to the barrier rib tops using a grinding method.

[0058] Here, if the central area of each barrier rib top is removed inthe first removing process, the amount of bonding agent that seeps intothe cell area after the panel has been sealed is further reduced.

[0059] Here, in the bond agent filling process, the bond agent may beapplied using a screen-printing method or a nozzle-injection method.

[0060] The second removing process removes the remainder of the firstmember using peeling, melting and sublimation.

[0061] The above first object may also be achieved by a display panelmanufacturing method, for connecting a pair of substrates arranged inopposition via a bonding agent applied to a plurality of barrier ribsformed on at least one of the substrates. A process for arranging thebonding agent on the barrier ribs includes an arranging process forbringing a bond sheet, made by forming a sheet of bonding agent inadvance, into contact with tops of the barrier ribs; a transfer processfor transferring the bonding agent to the parts of the barrier rib incontact with the bond sheet; and a removing process for separating thebond sheet from the barrier ribs.

[0062] Here, the bonding agent in the present invention is arranged onthe barrier rib tops with the bonding agent and the barrier rib tops inan accurately aligned state by bringing a bond sheet and the barrier ribtops into contact and transferring the bonding agent selectively tothose parts of the barrier rib tops touching the bond sheet. This methodis used rather than a screen plate with an aperture pattern like thatused in screen-printing. As a result, the bonding agent can be appliedevenly along the narrow barrier rib tops using a simple technique, evenif the barrier rib tops are not strictly linear, and form wavy lines.This enables a display panel with greater bonding strength to beobtained.

[0063] The transfer process may transfer the bonding agent to the partsof the barrier rib tops in contact with the bond sheet by pressing thebonding agent sheet onto the barrier rib tops.

[0064] The transfer process should preferably heat the parts of the bondsheet in contact with the barrier rib tops.

[0065] This gives the bonding agent greater adhesiveness, enabling it tobe transferred to the barrier rib tops with more reliability.

[0066] The above first object may also be achieved by a display panelmanufacturing method, for connecting a pair of substrates arranged inopposition via a plurality of barrier ribs formed on at least one of thesubstrates, and a bonding agent applied to the barrier ribs. The displaypanel manufacturing method includes an applying process for applying thebonding agent to an area on each barrier rib that is at least as largeas a top of each barrier rib; a hardening process for hardening parts ofthe attached bonding agent; and a removing process for removing theparts of the bonding agent that have not been hardened.

[0067] Here, the application area for the bonding agent is notestablished from the outset as in screen-printing. Instead, the bondingagent is arranged on the barrier rib tops, covering an area than iswider than the barrier rib tops. Parts of the arranged bonding agent arethen hardened and the parts that still remain soft are selectivelyremoved, leaving the bonding agent arranged appropriately along thebarrier rib tops. As a result, the bonding agent can be applied evenlyalong the narrow barrier rib tops using a simple technique, enabling adisplay panel with greater bonding strength to be obtained. If theaccuracy with which parts of. the bonding agent are hardened can beimproved, the bonding agent can be applied evenly along the narrowbarrier rib tops using a simple technique, even if the barrier rib topsare not strictly linear, and form wavy lines. This enables a displaypanel with even greater bonding strength to be obtained.

[0068] In the applying process, a compound of bonding agent andphoto-hardening resin is applied to the barrier rib tops; and in thehardening process, parts of the applied compound are exposed to light,causing the exposed parts of the compound to harden.

[0069] A resin that hardens upon exposure to ultra-violet light is usedas the photo-hardening resin, and the light used in the hardeningprocess may be ultra-violet light.

[0070] In the hardening process, after ultra-violet irradiation hastaken place, hardened parts of the bonding agent are heated.

[0071] This enables the hardened bonding agent to be more firmlyhardened.

[0072] The bonding agent is arranged on the barrier ribs using acompound including a first substance which is more difficult to meltthan the bonding agent.

[0073] The first substance supports the load of the front substrate,preventing bonding agent melted when the substrates are sealed frombeing pressed down by the weight of the front substrate and seeping intothe cell area. This stops the panel from being fired with bonding agentseepage inside the cell area.

[0074] Next, to achieve the above second object, the present inventionalso includes a gas discharge panel, including a first substrate, onwhich a plurality of pairs of electrodes extending in a first direction,and a dielectric layer covering the electrodes have been formed, and asecond substrate, on which a plurality of barrier ribs, extending in asecond direction differing from the first direction, are formed inopposition to the dielectric layer and the electrode pairs so that thebarrier ribs are separated from the dielectric layer and the electrodepairs. Here the dielectric layer and the barrier ribs are at leastpartially connected. The panel is structured such that discharge mainlyoccurs in parts of the panel separated from the positions where thebarrier ribs and the dielectric layer are connected.

[0075] This means that discharge does not occur equally throughout eachcell, but is more likely to occur in the parts of a cell distanced fromthe locations where the barrier ribs are connected than in those partsnear to the connected areas. Accordingly, the bonding agent applied tothe barrier rib tops is less likely to be exposed to discharge,preventing pigments, residual carbon, and the like from contaminatingthe discharge gas in the discharge spaces. As a result, increases indischarge voltage, deterioration of the phosphor layer, and reduction inluminance are less likely, and initial operating performance can besustained over the long term.

[0076] The panel structure described above may be formed in a variety ofways, as explained below.

[0077] One option is a panel structure in which the gaps between pairsof facing electrodes have both wide and narrow sections, and the narrowsections are formed in the spaces between the parts of the dielectriclayer to which the barrier ribs are connected. Another option is a panelstructure in which a protective layer covers the surface of thedielectric layer, aside from the parts of the dielectric layer where thebarrier ribs are connected. A further option is a panel structure inwhich the parts of the dielectric layer where the barrier ribs areconnected are thicker than the other parts of the dielectric layer. Yetanother option is a panel structure in which a protective layer isformed on the surface of the dielectric layer, and the barrier ribsconnected to the protective layer, so that the parts of the protectivelayer where the barrier ribs are connected have less surface roughnessthan the other parts of the protective layer. Yet another option is apanel structure in which a protective layer is formed on the surface ofthe dielectric layer, and the barrier ribs connected to the protectivelayer, so that the parts of the protective layer where the barrier ribsare connected are thicker than the other parts of the protective layer.Yet a further option is a panel structure in which parts of the barrierribs which do not correspond to cells are attached to the frontsubstrate. Another option is a panel structure in which the barrier ribsare partially connected to the first substrate with a bonding agent,which is applied to the barrier rib tops so that the area covered isnarrower than each barrier rib top.

[0078] The term ‘barrier rib tops’ in the last panel structure describedabove refers to a flat area on the top of each barrier rib, if thebarrier ribs have a level upper surface. Alternately, if the tops of thebarrier ribs have a curved surface, the term refers to an areadetermined by a value that is approximately double the size of theradius of the curved surface.

[0079] Gas should preferably be enclosed in the space between the firstand second substrates of the gas discharge panel at a pressure of notless than 760 torr.

BRIEF DESCRIPTION OF THE DRAWINGS

[0080]FIG. 1 is a cross-sectional diagram showing an outline of an ACsurface discharge PDP relating to the first embodiment;

[0081]FIG. 2 shows an outline of the structure of an ink applying deviceused when forming the phosphor layer;

[0082]FIG. 3 shows a method for arranging the bonding agent on the topsof the barrier ribs;

[0083]FIG. 4 shows a situation in which the barrier ribs are ofdifferent heights;

[0084]FIG. 5 shows how differences in the height of barrier ribs causevariations in the amount of coating applied;

[0085]FIGS. 6A and B show variations in the shape formed by the layer ofbonding agent;

[0086]FIG. 7 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0087]FIG. 8 illustrates the operation of a regulating means;

[0088]FIG. 9 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0089]FIG. 10 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0090]FIG. 11 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0091]FIG. 12 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0092]FIG. 13 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0093]FIG. 14 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0094]FIG. 15 shows an alternative regulating means;

[0095]FIG. 16 shows an alternative regulating means;

[0096]FIG. 17 shows an alternative regulating means;

[0097]FIG. 18 shows an alternative regulating means;

[0098]FIG. 19 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0099]FIG. 20 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0100]FIG. 21 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0101]FIG. 22 is a cross-sectional drawing showing the shape of a metalmold in another embodiment;

[0102]FIG. 23 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0103]FIG. 24 is a cross-sectional drawing showing the shape of a metalmold in another embodiment;

[0104]FIG. 25 illustrates a method for arranging the bonding agent onthe tops of the barrier ribs using the metal mold of FIG. 24;

[0105]FIG. 26 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0106]FIG. 27 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0107]FIG. 28 illustrates a process for peeling off a transfer film,occurring in the method for applying the bonding agent shown in FIG. 27;

[0108]FIG. 29 illustrates a process for peeling off a transfer film,occurring in the method for applying the bonding agent shown in FIG. 27;

[0109]FIG. 30 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs;

[0110]FIG. 31 illustrates a method used in another embodiment forarranging the bonding agent on the tops of the barrier ribs, which is analternative to the method for arranging the bonding agent shown in FIG.30;

[0111]FIG. 32 shows the situation when the tops of the barrier ribs arejoined to the protective layer with the bonding agent, with FIG. 32Ashowing the situation when a material including beads, from anotherembodiment is used, and FIG. 32B the situation when beads are not used;

[0112]FIG. 33 shows the positional relationship between the locations ofthe discharge electrode pattern and the barrier ribs coated with thebonding agent;

[0113]FIG. 34 is a perspective view of a laser processing device usedfor forming a transparent electrode pattern with a laser;

[0114]FIG. 35 shows the formation of the transparent electrodes and thepositional relationship of the transparent electrodes and the barrierribs which have been coated with the bonding agent, for a PDP in anotherembodiment;

[0115]FIG. 36 shows the protective layer pattern and the positionalrelationship between the protective layer and the barrier ribs coatedwith the bonding agent,, for a PDP in another embodiment;

[0116]FIG. 37 shows the dielectric glass layer pattern and thepositional relationship between the dielectric glass layer and thebarrier ribs coated with the bonding agent, for a PDP in anotherembodiment;

[0117]FIG. 38 shows the protective layer pattern and the positionalrelationship between the protective layer and the barrier ribs coatedwith the bonding agent, for a PDP in another embodiment;

[0118]FIG. 39 shows the positional relationship between the locations ofcells and the parts where the barrier ribs are connected in a PDPrelating to another embodiment;

[0119]FIG. 40 shows the results of an experiment performed toinvestigate the effects of the nineteenth embodiment;

[0120]FIG. 41 illustrates the formation of the bonding agent applied tothe barrier ribs; and

[0121]FIG. 42 shows a structure for a PDP relating to the background artexample.

BEST MODE FOR CARRYING OUT THE INVENTION

[0122] First Embodiment

[0123] An Overview of the General Structure of the PDP and the PDPManufacturing Method

[0124]FIG. 1 is a cross-sectional drawing of an AC surface discharge PDPrelating to the first embodiment of the invention. Only one cell isshown in the drawing, but in fact a PDP in which a plurality of cellsemitting red, green and blue light are arranged alternatively isconstructed. Note that in the drawing discharge electrodes 12 andaddress electrodes 16 are drawn as if arranged in parallel, but in factthey are arranged at right angles.

[0125] The PDP is an AC surface discharge panel inside which dischargeis caused by applying a pulse voltage to the electrodes. Discharge isaccompanied by the generation of visible light of various colors insidethe PDP near to a back substrate PA2 and this light passes through themain surface of a front substrate PA1.

[0126] The front substrate PA1 is formed in the following way. Dischargeelectrodes 12 are lined up in stripes on a front glass plate 11 and thisstructure is. covered with a dielectric glass layer 13, which is furthercovered with a protective layer 14. The discharge electrodes 12 areconstructed by forming transparent electrodes 12 a on the surface of thefront glass plate 11, and then forming metal electrodes 12 b on top ofthe transparent electrodes 12 a.

[0127] The back substrate PA2 is formed in the following way. Addresselectrodes 16 are lined up in stripes on a back glass plate 15, and thisstructure is covered with a visible light reflecting layer 17, whichprotects the address electrodes 16 and reflects visible light towardsthe front panel. Barrier ribs 18 are erected on the visible lightprotecting layer 17 in a direction parallel to the address electrodes16, so that each address electrode 16 seems to be sandwiched by twobarrier ribs 18. A phosphor layer 19 is applied to the spaces formedbetween the barrier ribs 18.

[0128] Manufacture of the Front Substrate PA1

[0129] The front substrate PA1 is manufactured by forming the dischargeelectrodes 12 on the surface of the glass plate 11, covering thedischarge electrodes 12 with a dielectric glass layer 13 and applying aprotective layer 14 to the surface of the dielectric glass layer 13.

[0130] The discharge electrodes 12 are formed in the following way.First, the transparent electrodes 12 a, made of a transparent,electro-conductive metal oxide such as indium tin oxide (ITO), areformed using a method such as sputtering. The pattern for the metalelectrodes 12 b is produced on top of this by applying silver pasteusing a printing method such as screen-printing or ink-jet printing, andthen firing the result. The metal electrodes 12 b may alternatively beconstructed from three layers, made respectively of chromium, copper andchromium (Cr—Cu—Cr).

[0131] The dielectric glass layer 13 is a composite formed by mixing aplurality of inorganic materials with an organic binder in which 10% ofethyl cellulose is dissolved in −α terpineol. The inorganic materialsmay be a composite of, for example, 70% lead oxide (PbO), 15% diborontrioxide (B₂O₃), 10% silicon dioxide (SiO₂) and 5% aluminum oxide. Thiscomposite is applied by a printing method such as screen-printing, andthen fired at a temperature of around 500° C. for about twenty minutesto produce a layer 30 μm thick (the figures here are all example values,and may be varied).

[0132] The protective layer 14 is composed of magnesium oxide (MgO) andapplied using a method such as electron beam vapor deposition.

[0133] Manufacture of the Back Substrate PA2

[0134] The back substrate PA2 is constructed in the following way.Address electrodes 16 are formed on a back glass plate 15, which is thencovered by a visible light reflecting layer 17. Barrier ribs 18 areformed on the surface of the visible light reflecting layer 17 and aphosphor layer 19 is formed between the barrier ribs 18.

[0135] The address electrodes 16 are produced in the same way as metalelectrodes 12 b, by applying silver paste to the surface of the backglass plate 15 using a printing method such as screen-printing orink-jet printing.

[0136] The visible light reflecting layer 17 is formed by printing asuitable material on top of the address electrodes 16 using a printingmethod such as screen-printing, and then firing it. A thin layer of thesame kind of glass composite as was used for the dielectric glass layer13, further including particles of titanium oxide (TiO₂), is suitablefor this purpose.

[0137] The barrier ribs 18 are produced by applying a material using amethod such as screen-printing, lift-off or sand-blasting, firing theresult, and then processing the tops of the barrier ribs 18. The barrierribs 18 thus formed are shaped as shown in FIG. 41. From the drawing, itcan be seen that the barrier ribs 18 are trapezoid in cross-section andhave exposed surfaces. The trapezoid is composed of an upper surface 18a, which is roughly parallel to the plates, and a side part 18 b, whichwill later be in contact with the phosphor layer.

[0138] The phosphor layer 19 may be formed using any well-known method,such as screen-printing, or by a nozzle-spraying method described below.

[0139]FIG. 2 is an outline drawing of the construction of an inkapplying device 30, used in producing the phosphor layer 19. Firstphosphor powder, terpineol and ethyl cellulose are introduced into aserver 31 to form phosphor ink 34. The phosphor ink 34 is sprayed from anozzle 33 of a spray device, under pressure from a pump 32. Phosphorlines in each of the three colors are formed by spraying the phosphorink 34 in stripes into the spaces between the barrier ribs 18, whilesimultaneously moving the substrate in a straight line. The phosphorlayer 19 is finished by firing at a certain temperature of around 500°C.

[0140] Phosphors commonly used in the art, such as those describedbelow, may be used to produce the phosphor lines. Red phosphor:Y₂O₃:Eu³⁺ Green phosphor: Zn₂SiO₄:Mn Blue phosphor: BaMgAl₁₀O₁₇:Eu²⁺

[0141] Finishing the PDP by Fixing the Substrates Together

[0142] Next, front substrate PA1 and the back substrate PA2 are sealedtogether with the discharge electrodes 12 at right angles to the addresselectrodes 16. This-is achieved by pressing the tops of the barrier ribs18 coated with a bonding agent onto the surface of the protective layer14 on the front substrate PA1 and firing the PDP. The PDP is completedby enclosing a discharge gas (a mixture of inert gases with, forexample, a He—Xe or Ne—Xe base) inside the discharge spaces 20 definedby the barrier ribs 18.

[0143] In the present embodiment, the pressure of the enclosed inert gasis set at a high level of at. least 760 torr, and at least as great asatmospheric pressure.

[0144] The reason for using this kind of high pressure is that the shapeof the discharge is likely to be altered, enabling a linear glowdischarge or a two-phase glow discharge to be more easily produced,rather than simply producing a conventional one-phase glow discharge.This increases electron density in the positive column of the discharge,allowing energy to be supplied in a concentrated fashion. Resultingincreases in ultra-violet light emissions and the like improve luminousefficiency and allow high luminance levels to be obtained. A moredetailed description of this process can be found in Japanese PatentApplication No. 10-229640.

[0145] The following is a description of the main point of thisinvention: a method for fixing the front substrate PA1 and the backsubstrate PA2 together, and in particular a method for applying abonding agent for fixing the barrier ribs 18 and the protective layer 14to the barrier ribs 18 in order.

[0146] The Panel Fixing Method, Concentrating on the Method for Applyinga Bonding agent Bd to the Barrier Ribs 18

[0147] As explained above, inert gas is introduced into the dischargespaces 20 of the PDP in the present embodiment at a pressure higher thanatmospheric pressure in order to improve luminous efficiency.

[0148] Accordingly, the front substrate PA1 and the back substrate PA2need to be fixed firmly together so as to withstand this pressure. Thefront substrate PA1 and the back substrate PA2 are connected, with thebarrier ribs 18 used as spacers. When a conventional screen-printingmethod is used to apply a bonding agent to the barrier ribs 18, however,it is difficult to coat the entire upper surfaces of the barrier ribs 18evenly. The shape of the coating differed from the ideal shape describedabove, so that after the substrates were connected, the bonding agentspread out over a wide area stretching as far as the cell area, therebyreducing the amount of light-producing surface area in the cells. Thismeant that the effects gained from enclosing the gas at a higherpressure were not as great as expected. The application method in thepresent embodiment, however, can apply the bonding agent Bd to thebarrier ribs 18 evenly, achieving a shape close to the ideal shape, asdescribed below.

[0149]FIG. 3 illustrates a method for forming the bonding agent Bd onthe tops of the barrier ribs. The application process takes place in thestages (1) to (4) shown in FIG. 3.

[0150] In stage (1), a paste layer 40 formed from the bonding agent Bdis applied to the surface of a flat plate 41, made of glass or the like.Both the surface of the flat plate 41 and the paste layer 40 are even.The paste layer 40 may be applied by spreading the bonding agent Bdacross the surface of the flat plate 41, using a wire bar or similar asa squeegee, or by using a dye coating method. The paste used as thebonding agent Bd is a composite formed by tempering a glass frit. withan acrylic resin and a solvent such as terpineol. The frit is glass witha low softening point, such as around 500° C., mixed with a filler madeof ceramic particles or similar. The filler serves as a thermalexpansion conditioner to cope with the volume changes experienced by thebonding agent Bd during firing. It is the glass with a low melting pointthat mainly functions as the bonding agent when the barrier ribs 18 andthe front substrate PA1 are fixed together. Glass with a low meltingpoint that includes a black pigment may also be used for this purpose.If such a black pigment is used, a visual effect, in which the variouslycolored light emitted by the screen appears more brilliant, is obtained.The paste used for the bonding agent Bd should preferably have a highviscosity. If a paste with a low viscosity is used, it runs down thesides of the barrier ribs 18 when applied, and is thus likely to seepinto the already formed phosphor layer. Thus, a paste with a viscosityof between 50 and 300 Pa.s should preferably be used.

[0151] Next, in stage (2), the outer surface of the back panel PA2 isgripped by base 42 so that-the opposing surfaces of the back panel PA2on which the barrier ribs 18 and the phosphor layer have been formed,and the flat plate 41 are almost parallel. The base 42 includes amechanism for sliding the flat plate 41 up and down while keeping it inparallel with the base 42. The back panel PA2 is gripped by the base 42using sufficient suction to eliminate the curvature of the back glassplate 15. Thus, the base 42 enables the flat plate 41 and the backsubstrate PA2 to be kept roughly in parallel.

[0152] In stage (3), the base 42 is slowly moved a specified amountuntil the tops 18a of the barrier ribs 18 and the paste layer 40substantially coincide, bringing the barrier ribs 18 into contact withthe paste layer 40.

[0153] Next, in stage (4), the base 42 is slowly moved in the oppositedirection, separating the barrier ribs 18 from the paste layer 40.

[0154] By following the processing sequence described above, the bondingagent Bd is applied evenly to virtually the entire surface of the tops18 a of the barrier ribs 18, which are narrow areas running the lengthof each barrier rib 18. Moreover, the bonding agent Bd is applied sothat a shape close to the ideal one described above is obtained.

[0155] The reason the barrier ribs 18 are moved slowly into contact withthe paste layer 40 is to ensure that the bonding agent Bd is appliedevenly. If the barrier ribs 18 enter the paste layer 40 suddenly,irregularities can be caused by inertia. In addition, if the barrierribs 18 are extracted too suddenly from the paste layer 40, the bondingagent Bd may be shaken loose by mechanical vibrations caused by themotor moving the base 32.

[0156] The bonding agent Bd can be applied so as to form a nearly idealshape, that is to say thickly along the center of each barrier rib 18,and more thinly to the areas on either side of this strip, due to thebonding agent Bd being applied to the surface of the barrier ribs 18using surface tension when the tops of the barrier ribs 18 are dipped inthe bonding agent Bd.

[0157] In practice, however, there is a certain amount of variation inthe heights of the barrier ribs 18, and differences in height can alsobe observed along the length of individual barrier ribs 18. This iscaused, among other things, by a slight curvature in the glass plate onwhich the barriers ribs 18 are fixed, and by the conditions under whichthe barrier ribs 18 are formed.

[0158]FIG. 4 shows a situation in which this kind of unevenness in theheight of the barrier ribs exists.

[0159] The above variation in the height of the barrier ribs 18 causesthe consistency with which the bonding agent Bd is applied to thebarrier ribs 18 to be influenced by the distance base 42 is moved, thatis the degree to which the barrier ribs 18 are brought into contact withthe paste layer 40.

[0160] This means that if the degree of contact of the barrier ribs 18with the paste layer 40 is too low, as is shown in FIG. 4A, relativelylow parts of the barrier ribs 18 will not be coated with the bondingagent Bd. This is likely to cause problems when the barrier ribs 18 arefixed to the front glass plate, and may produce a defective productunable to withstand high pressure.

[0161] When the heights of the barrier ribs 18 vary in this way, amethod described below may be used to adjust the degree of contactbetween the barrier ribs 18 and the paste layer 40 appropriately so thatthe bonding agent Bd can be applied without the variations in heightaffecting the result. FIG. 4B shows a method in which the bonding agentBd is applied evenly to the entire upper surface of each barrier rib 18by adjusting the amount that the base 42 is moved.

[0162] As shown in the drawing, all of the barrier ribs 18 can be evenlycoated with the bonding agent Bd by moving the base 42 until the pointat which the barrier ribs 18 are lowest (W1 in the drawing) is broughtinto contact with the paste layer 40.

[0163] If the bonding agent Bd is applied to all of the barrier ribs 18using the method shown in FIG. 4B, the higher barrier ribs 18 have alarger degree of contact with the paste layer 40 and are thus coatedwith a larger amount of the bonding agent Bd than lower barrier ribs 18.This means that when the front substrate PA1 and the back substrate PA2are sealed together, there will be greater seepage of the bond into cellareas corresponding to higher barrier ribs 18, as was described above.As a result, the light-emitting cell area is decreased, and luminancewill probably fall.

[0164] With this in mind, the following is an explanation of how theamount of coating comes to vary with the height of the barrier ribs 18with reference to the model representation in FIG. 5. The drawing showsa situation in which the amount of coating varies according to theheight of the barrier ribs 18. As shown in the drawing, the amount ofbonding agent Bd applied increases with the height of the barrier ribs18 (in the order A, B, C, in the case of the barrier ribs in thedrawing). When the front substrate PA1 and the back substrate PA2 aresealed together with the bonding agent Bd applied in this fashion, thebonding agent Bd applied to the barrier rib C will seep into a widercell area than the bonding agent applied to the other barrier ribs A andB. Furthermore, if neighboring barrier ribs 18 both have a large coatingof bonding agent Bd, the degree of seepage into the cell area betweensuch barrier ribs 18 will be even greater than if only a singletonbarrier rib 18 is affected.

[0165] Here, the tops 18 a of the barrier ribs 18 may be reduced bypolishing with a reduction device such sandpaper or a sander belt (apolishing device which supplies a continuous belt of sandpaper to apolishing part) or by grinding with a surface grinder. This minimizesvariations in the heights of the barrier ribs 18. The tolerated degreeof variation depends on how much influence the degree of seepage intothe cell area after connection has on luminance, but to give oneexample, a variation of around 10 μm would be acceptable when thebarrier ribs 18 are 100 μm in height.

[0166] In this sense, the meaning of the phrase the ‘tops of the barrierribs’ as used in the present and subsequent embodiments refers not justto the upper surface 18 a, but also to parts of the barrier rib sides 19b adjacent to the back substrate PA2 that are prone to some degree ofbonding agent seepage. Note that the tops 18 a of the barrier ribs 18may also be ovoid, triangular or jagged in shape.

[0167] The polishing process may be performed on the tops 18 a of thebarrier ribs 18 either before or after the phosphor layer is formed. Itis preferable to perform the process beforehand however, since thisprevents dust created by the polishing or similar from lodging betweenthe phosphor particles.

[0168] Once the bonding agent Bd has been applied to the tops 18 a ofthe barrier ribs 18 as explained above, a similar bonding agent isapplied to the perimeter of either the front substrate PA1 or the backsubstrate PA2 as a sealant.

[0169] Next, pre-firing takes place at a specified temperature of aroundsay 350° C., in order to eliminate resinous components from the sealingpaste applied to the perimeter of the substrates.

[0170] Then, the front substrate PA1 and the back substrate PA2 areplaced in opposition with the discharge electrodes 12 and the addresselectrodes 16 at right angles. The substrates are then sealed togetherby firing at a specified temperature of, for example, 450° C.

[0171] The paste layer 40 need not be formed on the flat plate 41, aslong as its surface can be kept even. As shown in FIG. 6A, the pastelayer 40 may be formed by filling a paste container 43 with the bondingagent Bd, and smoothing the surface using a squeegee or similar.Alternately, as shown in FIG. 6B, the bonding agent Bd may be appliedevenly to the surface of a paste film 44 made from polyethylene or thelike, which is used instead of the flat plate 41 to create anevenly-shaped layer.

[0172] Second Embodiment

[0173] This embodiment is characterized by a mechanism for adjusting thedegree of contact between the bonding agent and the barrier ribs, so thefollowing explanation focuses on this device.

[0174]FIG. 7 shows a method for forming the bonding agent Bd on the topsof the barrier ribs 18. The processing sequence for applying the bondingagent Bd is performed in the order of the numbered stages (1) to (5).

[0175] First, in stage (1), mesh 51 is placed on the flat plate 41(identical to that in FIG. 3). The mesh 51 is formed by weaving wirerods made of metal or a resin such as polyethylene together, with thewire rods spaced at specified intervals. A mesh of the size used inconventional screen-printing, such as a 325 mesh, may be used. It ispreferable to use a finer mesh, however, since the reduction in thethickness of the wire rods used to construct the mesh 51 means that themesh pattern is less likely to remain on the surface of the barrier ribs18 when the bonding agent Bd is applied, enabling the bonding agent Bdto be applied evenly.

[0176] In stages (2) and (3), a squeegee 52 is used to apply the bondingagent Bd from the top surface of the mesh 51 (the upper side in thedrawing) forming a paste layer 50 of the same thickness as the mesh 51.The paste layer 50 is held in place by the mesh 51. A specified amountof the bonding agent Bd is placed on one part of the mesh 51, and spreadby moving the squeegee 52 across the surface of the mesh 51.Alternately, the paste layer 50 may be formed by using a printing meanssuch as dye coating. The squeegee 52 may be made of rubber, but as arubber squeegee leaves lines behind, a metal squeegee should preferablybe used to obtain a more even finish.

[0177] In stage (4), a back substrate PA2, with the barrier ribs 18 andthe phosphor layer 19 formed on its surface, is prepared. The barrierribs 18 are then pushed into contact with the surface of the paste layer50.

[0178] Here, the pressure brought to bear on the mesh 51 is sufficientto press down the mesh 51 to compensate for the variations in the heightof the barrier ribs 18, ensuring that the bonding agent Bd is appliedevenly to virtually all of the tops 18 a of the barrier ribs 18.

[0179] Next, in stage (5), the back substrate PA2 is separated from themesh 43.

[0180] By using the above process, the bonding agent Bd can be appliedevenly to virtually the entire length of the top of each barrier rib 18,so that the paste layer 50 is formed in a shape similar to that of theideal shape described above.

[0181] In this way, in the present embodiment, the mesh 51 serves as aregulator for regulating the degree of contact obtainable with the pastelayer 50. FIG. 8 shows an enlargement of part of the mesh 51 in order toillustrate this process. As can be seen from the drawing, the degree ofcontact between the barrier ribs 18 and the paste layer 50 is regulatedby the parts M1 and M2 where the barrier ribs 18 touch the mesh 51.

[0182] In other words, the paste layer 50 held in place by the mesh 51used here is formed so as to be of the same thickness as the mesh 51.This means that when the barrier ribs 18 are pressed down, the tops 18 aof the barrier ribs 18 are regulated by the parts M1 and M2 near to thesurface of the paste layer 50, enabling the bonding agent Bd to beapplied evenly to virtually the entire surface of the barrier rib tops18 a.

[0183] Note that the bonding agent Bd may splatter up from the surfaceof the mesh 51 when the mesh 51 is pressed down, but as long as theamount of the bonding agent Bd which seeps into the cell area is notsufficient to have a great impact on luminance, say of about 10 μm whenthe barrier ribs 18 have a height of 100 μm, this is acceptable.

[0184] Furthermore, the pattern of the mesh 51 is more likely to be lefton the barrier ribs at places where the barrier ribs 18 and the mesh 51come into contact, but this problem can be solved by repeating the aboveprocess.

[0185] The mesh pattern left on the barrier ribs 18 can also beeliminated by moving the back substrate PA2 horizontally along thelength of the barrier ribs 18 while pressing it down onto the mesh 51.By moving the: back substrate PA2 in this way, the bonding agent Bdadheres to the parts of the barrier ribs 18 which were previously incontact with the mesh 51, and which were thus unable to receive acoating of bonding agent Bd.

[0186] The tops 18 a of the barrier ribs 18 are often concave. If thebonding agent Bd cannot be applied to such concave top surfaces, thefront substrate PA1 and the barrier ribs 18 will not be properlyconnected in these areas, lowering display quality. However, moving thefront substrate PA1 in the way described above allows the bonding agentBd to be applied to such indentations in the tops 18 a of the barrierribs, so that the front substrate PA1 and the back substrate PA2 can bemore strongly bonded together.

[0187] Third Embodiment

[0188] This embodiment is characterized by a mechanism for pressing thebarrier ribs against the mesh, so the following explanation concentrateson this mechanism.

[0189]FIG. 9 illustrates a method used in the present embodiment forapplying the bonding agent to the tops of the barrier ribs.

[0190] First, the mesh 51 (the same as in FIG. 7) is arranged on asurface of a cylindrical roller 61. Next, squeegees 62 are fittedagainst the surface of the mesh 51 and the bonding agent Bd fills up themesh 51 arranged on the surface of the roller 61, forming a paste layer60 held in place by the mesh 51. The bonding agent Bd is supplied in anappropriate amount onto the squeegees 62 from a tank 63.

[0191] Then, the roller 61 is pressed onto the back substrate PA2 onwhich the barrier ribs 18 and the phosphor layer 19 have been formed. Bymoving the back substrate PA2, the entire length of each barrier rib 18,starting from one end of the barrier ribs 18, is brought into contactwith the mesh 51, applying the bonding agent Bd evenly to almost theentire top surface 18 a of each barrier rib 18, producing a shape closeto that of the ideal shape.

[0192] Here, it is preferable that the roller 61 is pressed against theback glass panel 43 using a back-up roller (not shown) arranged inparallel with the roller 61. The direction in which the back substratePA2 moves may be a direction in which it is pushed by the roller 61 or adirection counter to that of the roller 61. The drawing shows the lattersituation.

[0193] An attachment base, which grips the back substrate PA2, and fixesit in place, may be used instead of the back-up roller as the mechanismfor pressing the mesh 51 onto the back substrate PA2. Although not shownin FIG. 9, the width of the mesh 51 corresponds to the width of thesubstrate PA2, enabling the mesh 51 to come into contact with all of thebarrier ribs. The same applies to the mesh in the following embodiments.

[0194] Fourth Embodiment

[0195] This embodiment is characterized by a mechanism for pressing thebarrier ribs against the mesh, so the following is an explanation ofthis mechanism.

[0196]FIG. 10 illustrates a method for applying the bonding agent to thetops of the barrier ribs in the present embodiment.

[0197] As shown in the drawing, the mesh 51 has a belt-like structure,running between a roller 71 and a roller 72 via a roller 61. A squeegee73 is arranged at a position where the mesh 51 wound out from the roller71 touches the roller 61, enabling the bonding agent to fill up the mesh51, which holds the layer of bonding agent in place. A tank 74 suppliesan appropriate amount of bonding agent Bd onto the squeegee 73.

[0198] If the back panel PA2, complete with barrier ribs 18 and thelike, is moved horizontally, the mesh 51 filled with bonding agent Bdcomes into contact with each of the barrier ribs 18 in turn. Thisenables the bonding agent Bd to be applied evenly to the virtually theentire length of the top surface of each barrier rib 18, so that theshape formed is similar to the ideal shape.

[0199] The mesh 51 may also be run over the rollers 71, 61 and 72 usingan endless belt-like structure like the one shown in FIG. 11.

[0200] Here, as in the third embodiment, the roller 61 should preferablybe pressed against the back substrate PA2 using a back-up roller. Thedirection in which the back substrate PA2 moves may be a direction inwhich it is pushed by the roller 61 or a direction counter to that ofthe roller 61. The drawing shows the latter situation. Also, as in thethird embodiment, an attachment base, which grips the back substratePA2, fixing it in place, may be used instead of the back-up roller asthe mechanism for pressing the mesh 51 onto the back substrate PA2.

[0201] Fifth Embodiment

[0202] This embodiment is characterized by a mechanism for pressing thebarrier ribs against the mesh, so the following explanation focuses onthis mechanism.

[0203]FIG. 12 illustrates a method for forming the bonding agent Bd onthe tops of the barrier ribs 18 in the present embodiment.

[0204] Here, a base 81 with a smooth curved surface is used instead ofthe roller 61 shown in FIG. 9. The mesh 51 is arranged on the curvedsurface of the base 81. Next, the surface of the mesh 51 is filled bythe bonding agent Bd using a squeegee or similar as explained above,forming a paste layer 80 held in place by the mesh 51.

[0205] Then the bonding agent Bd is applied to the surface of the backsubstrate PA2, on which barrier ribs 18 have been formed, by pressingthe base 81 onto the surface of the back substrate PA2 so that it rocksback and forth between the location shown by the solid lines and thelocation shown by the dotted lines in FIG. 12. This enables the bondingagent Bd to be applied evenly to virtually the entire length of the. topsurface of each barrier rib 18, so that the shape formed is similar tothe ideal shape.

[0206]FIG. 12 shows one example of a method for moving the base 81. Inthis method a pair of cylinders 82 capable of movement on a verticalplane are attached to either end of the base 81. Moving the cylinders 82in different directions at an appropriate speed makes it possible tomove the base 81 up and down. The driving mechanism for the cylindersmay be of a hydraulic pressure, pneumatic pressure or mechanical type.

[0207] As an alternative, the base 81 may be fixed and the backsubstrate PA2 rocked back and forth.

[0208] Sixth Embodiment

[0209] This embodiment is characterized by a mechanism for pressing thebarrier ribs against the mesh, so the following explanation focuses onthis mechanism.

[0210]FIG. 13 is a drawing illustrating a method used in the presentembodiment for forming the bonding agent Bd on the tops of the barrierribs 18.

[0211] In the examples given in the previous embodiments, the mesh 51 isarranged on the surface of a rigid body, such as a flat plate or aroller. However, the bonding agent Bd may also be applied to the barrierribs 18 by filling the mesh 51 with the bonding agent Bd and bringingthe mesh 51 alone into contact with the surface before lifting it awayagain. This process is shown in FIG. 13, stages (1) and (2). Thisenables the bonding agent Bd to be applied evenly to virtually theentire length of the top surface 18 a of each barrier rib 18, so thatthe shape formed is similar to the ideal shape. A tank 63 supplies anappropriate amount of bonding agent onto squeegees 62.

[0212] As shown in FIG. 13, the mesh 51 is brought into contact with thetops 18 a of the barrier ribs 18 while being wound onto a roller 83. Themesh 51 is lifted away from the barrier ribs 18 after the winding rollerhas been stopped.

[0213] In this example, the mesh 51 may be slid across the tops of thebarrier ribs 18 or the back panel PA2 may be slid across the mesh 51.

[0214] Seventh Embodiment

[0215] The method for applying the bonding agent in this embodiment isperformed by bringing the barrier ribs 18 into partial contact with thebonding agent Bd and then moving the back substrate PA2 so that thesurface tension between the barrier ribs 18 and a paste layer 90 allowsthe bonding agent to be applied along the entire length of the barrierribs 18.

[0216]FIG. 14 illustrates this method. Note that only one barrier rib isshown for the sake of simplicity.

[0217] In stage (1), one end of the upper surface 18 a of the barrierrib 18 is dipped in a paste layer 90. The barrier rib 18 is thenseparated from the paste layer 90 by a certain distance that allows thebonding agent Bd to adhere to the dipped part of the rib 18 due tosurface tension.

[0218] Next, as shown in stages (2) and (3), the back substrate PA2 onwhich the barrier rib 18 is formed is moved across the surface of thepaste layer 90, preserving the surface tension connecting the bondingagent Bd to the barrier rib 18. The bonding agent Bd may be appliedalong the barrier rib 18 by moving the back substrate PA2 in thedirection of the part of the rib as yet uncovered by the bonding agentBd, or in the opposite direction. This enables the bonding agent Bd tobe applied to virtually the entire surface of the tops 18 a of thebarrier ribs 18 using surface tension.

[0219] Note that a device like the one shown in FIG. 15, in which wirerods 91 are lined up regularly in a stripe formation, may be usedinstead of a mechanism in which the mesh 51 is placed on the roller 61,the flat plate 41, or similar. If the gaps between the wire rods 91 arefilled with the bonding agent Bd, the degree of contact between thebonding agent Bd and the barrier ribs 18 can be regulated by bringingthe barrier ribs 18 into contact with the wire rods 91, obtaining asimilar effect to that described above. The wire rods 91 should bearranged at a narrower pitch than the barrier ribs 18, ideally at apitch obtained by dividing the pitch of the barrier ribs 18 by aninteger. This makes it easier to locate the tops 18 a of the barrierribs 18 at a gap between two wire rods 91, in other words an areacontaining the bonding agent Bd, as can be seen from FIG. 18.

[0220] Alternatively, a device formed from a sheet of resin of an equalthickness, having a surface covered with slight protrusions andindentations, or a device in which protrusions and indentations of thesame height are formed directly on the surface of the flat plate 41, maybe used. The protrusions and indentations on the surface of the resinmay be formed by etching or by a molding machine.

[0221] Other alternatives are shown in FIGS. 16 and 17. FIG. 16 shows adevice formed by lining up a plurality of rectangular solids 92 on thesurface of the flat plate 41. FIG. 17 shows a device formed by lining upa plurality of approximate semi-hemispheres 93 on the surface of theflat plate 41.

[0222] Alternatively, a plurality of half-cylinders 94 may be lined upon the surface of the flat plate 41, as shown in FIG. 18. In this case,the half-cylinders 94 should be lined up lengthwise at regularintervals, at a pitch narrower than the pitch of the barrier ribs 18,and ideally at a pitch obtained by dividing the pitch of the barrierribs 18 by an integer. This means that the tops of the barrier ribs 18are lined up with the valleys between each of the half-cylinders 94, asshown in FIG. 18. In other words, the above structure makes it easier toposition the barrier ribs at locations containing the bonding agent Bd.

[0223] Note that the bonding agent application in the above first toseventh embodiments may be performed either before or after the phosphorlayer is formed between the barrier ribs.

[0224] Eighth Embodiment

[0225] This embodiment is characterized by a method for arranging thebonding agent on the tops of the barrier rubs, so the followingexplanation focuses on this method.

[0226]FIG. 19 is a process diagram showing a method for arranging thebonding agent in the present embodiment. The processing sequence isperformed in the order of stages (1) to (5).

[0227] In stage (1), a base plate 101 in which the address electrodes 16and the visible light reflecting layer 17 are formed on top of the backglass plate 15 is prepared. Following this, in stage (2), photosensitivefilm 102 is fixed to the surface of the base plate 101. Then apertures103 are formed in the photosensitive film 102 by exposing and developinga specific pattern, so that a pattern for the barrier ribs is obtained.

[0228] Next, in stage (3), a barrier rib forming paste 104 (hereafterreferred to as a barrier rib paste) for making the barrier ribs 18 isintroduced into the apertures 103 and then dried.

[0229] Following this, in stage (4), a bond paste 105 made of thebonding agent is introduced on top of the barrier rib paste 104 anddried. This creates a formation in which the barrier ribs 18 and thebonding agent Bd are laminated. Note that when the barrier rib paste 104is introduced, a round indentation 104 a is formed along the center ofeach barrier rib 18, as shown in stage (3).

[0230] In stage (5), the structure is transferred onto the base plate101 by eliminating the photosensitive film 102.

[0231] The structure is then fired, forming barrier rib and bondingagent layers, the layer of bonding agent Bd being arranged evenly alongthe barrier rib tops.

[0232] In general, the firing temperature for the barrier rib paste ishigher than that for the bonding agent Bd, so that in the above processthe bonding agent Bd is heated at a temperature higher than itssoftening point. Accordingly, if the surface on which the barrier ribs18 are formed is placed face down during firing, the bonding agent Bdcan be prevented from seeping into the barrier rib side.

[0233] Note that the bonding agent application in this embodiment may beperformed either before or after the phosphor layer is formed betweenthe barrier ribs.

[0234] Ninth Embodiment

[0235] This embodiment is characterized by a method for arranging thebonding agent on the tops of the barrier ribs, so the followingexplanation focuses on this method.

[0236]FIG. 20 is a process diagram showing a method for arranging thebonding agent in the present embodiment. The processing sequence isperformed in the order of the stages (1) to (5).

[0237] In stage (1), a base plate 201, in which the address electrodes16 and the visible light reflecting layer 17 are formed on top of theback glass plate 15 is prepared.

[0238] Next, in stage (2), a green sheet 202 is applied to the surfaceof the base plate 201 using a roller 203. The green sheet 202 is formedfrom a resinous film 202 a, a bonding paste layer 202 b and a barrierrib paste layer 202 c. The resinous film 202 a is formed from PET resin(polyethylene terephthalate) or similar. The bonding paste layer 202 bmay be formed by dispersing a glass frit with a low softening point andacrylic resin (IBM-1 developed by Sekisui Plastics Co.,Ltd) in2-butanone. The barrier rib paste layer 202 c may be formed from acomposite of an inorganic filler, glass frit and acrylic resin.

[0239] The green sheet 202 is manufactured in the following way. First,a coating of the bonding paste having a specified thickness of, forexample, 10 μm is applied on top of the resinous film 202 a using aprinting method such as a coater method, and then dried to form thebonding paste layer 202 b. Next, a coating of the barrier rib pastehaving a specified thickness of, for example, 120 μm is applied on topof the bonding paste layer 202 b and then dried to form the barrier ribpaste layer 202 a.

[0240] Following this, in stage (3), the resinous film 202 a is peeledoff from the green sheet 202 and the remaining layers are pre-fired.After this, a photosensitive film 204 is applied to the top of thebonding paste layer 202 b.

[0241] Next, in stage (4), apertures 205 are formed in thephotosensitive film 204 by exposing and developing a specific pattern,so that apertures 205 are formed in a pattern corresponding to thepattern of the barrier ribs 18 and the bonding agent Bd.

[0242] Then, in stage (5), the green sheet 202 is removed from beneaththe apertures 205 created in the photosensitive film 204 patterned asdescribed above. This process is performed by blowing minute particlesof silica or similar against the surface of the green sheet 202 using asandblasting method. A structure in which the barrier ribs 18 andbonding agent Bd have been laminated is obtained.

[0243] In stage (6), the photosensitive film 204 is removed,transferring the aforementioned structure onto the base plate 201.

[0244] Finally, this structure is fired, forming barrier rib and bondingagent layers, the layer of bonding agent being arranged evenly along thebarrier rib tops. Note that if the surface on which the barrier ribs 18are formed is placed face down during this firing process, the bondingagent can be prevented from seeping into the barrier rib side.

[0245] In this embodiment the green sheet consisted of three layersincluding a resinous film, but the resinous film is a backing sheet,which need not be used.

[0246] Furthermore, the barrier rib paste and the bonding paste may beapplied using a printing method rather than the green sheet.

[0247] Tenth Embodiment

[0248] This embodiment is characterized by a method for arranging thebonding agent on the tops of the barrier ribs, so the followingexplanation concentrates on this method.

[0249]FIG. 21 is a process diagram showing the method for arranging thebonding agent in the present embodiment. The processing sequence isperformed in the order shown by stages (1) to (4).

[0250] In stage (1), a base plate 301 in which the address electrodes 16and the visible light reflecting layer 17 are formed on top of the backglass plate 15 is prepared.

[0251] Following this, in stage (2), the base plate 301 is placed, withthe surface on which the address electrodes 16 have been formed facingdownwards, on a metal mold 303 with a green sheet 302 sandwiched inbetween. The green sheet 302 is formed from a bonding paste layer 302 aand a barrier rib paste layer 302 b, so that a green sheet that isidentical to the green sheet 202 with the resinous film omitted may beused. The metal mold 303 is formed in the shape of the barrier ribpattern.

[0252] Next, stage (3), the green sheet 302 is pushed down by the baseplate 301. This is performed with the base plate 301 and the metal mold303 heated to a temperature that is sufficient to melt the green sheet302. This produces a structure in which the barrier ribs 18 and thebonding agent Bd have been laminated.

[0253] In stage (4), the temperature is lowered to one at which thegreen sheet 303 is no longer fluid, and the base plate 301 is separatedfrom the metal mold 303, transferring the aforementioned structure ontothe base plate 301.

[0254] Finally, this structure is fired, forming barrier rib and bondingagent layers, the layer of bonding agent being arranged evenly along thebarrier rib tops 18 a. Note that pressure causes the bonding agent Bdlocated at areas other than the barrier rib tops 18 a to be mixed inwith the material used to form the barrier ribs 18, so that a layer ofbonding agent is formed on the barrier rib tops 18 a and not anywhereelse on the surface of the barrier rib material. Furthermore, thesurface on which the barrier ribs 18 have been formed should preferablybe placed face down during the firing process, as was the case in theeighth embodiment.

[0255] Additionally, when the pattern of the barrier ribs 18 and bondingagent Bd is formed using a metal mold, as shown in stage (4), thematerial used to form the barrier ribs 18 is left on the surface of thelight reflecting layer 17 in the gaps between the barrier ribs 18 shownby 302 c in the drawing). This material may be removed by a method suchas post-pattern-formation cutting.

[0256] Eleventh Embodiment

[0257] This embodiment is characterized by a metal mold used in a methodfor arranging the bonding agent on the tops of the barrier ribs, as inthe tenth embodiment, so the following explanation concentrates on thismetal mold.

[0258] In the present embodiment, the metal mold has a unique shape, asshown in FIG. 22. In other words, the metal mold 401 is shaped so thatan even protrusion 404 is formed along the length of the bottom part 403of each of the troughs 402 which make up the pattern for the barrierribs.

[0259] Accordingly, in the process for pushing down the base plate ontothe metal mold 401, the green sheet is pushed down by a base plate,inserting the bonding agent 302 b into the indentations on either sideof the protrusion 404, as shown in FIG. 22. This determines the locationof the barrier ribs 18 and the bonding agent Bd, so that the bondingagent Bd is arranged more accurately on the barrier ribs 18.

[0260] Note that the protrusions 404 need not be formed along the entirelength of the bottom part 403 of each barrier rib 18, but may instead beplaced at intervals.

[0261] Twelfth Embodiment

[0262] This embodiment is characterized by a method for arranging thebonding agent on the tops of the barrier ribs, so the followingexplanation concentrates on this method.

[0263]FIG. 23 is a process diagram showing the method for arranging thebonding agent in the present embodiment. The processing sequence isperformed in the order shown by stages (1) to (5).

[0264] First, in stage (1), a base plate 501 in which the addresselectrodes 16 and the visible light reflecting layer 17 are formed onthe back glass plate 15 is prepared.

[0265] Next, in stage (2), the base plate 501 is placed with the surfaceon which the address electrodes 16 have been formed facing downwards ona metal mold 503 with a green sheet 502 sandwiched in between. The greensheet 502 is formed only from a barrier rib paste layer, so that a greensheet which is the green sheet 202 with the resinous film and thebonding paste layer omitted is used. The metal mold 503 has the samepattern as the metal mold 403, being formed in the pattern of thebarrier ribs 18, with a protrusion formed along the length of the bottomof each trough.

[0266] Next, in stage (3), the green sheet 502 is pushed down by thebase plate 501 while being heated. This enables a structure in which anindentation 504 (see FIG. 23, stage (4)) is formed along the top of eachbarrier rib to be obtained.

[0267] In stage (4), the base plate 501 is separated from the metal mold503, transferring the above structure to the base plate 501.

[0268] In stage (5), a bonding paste 505 is applied to the indentation504 using a screen-printing method, the film transfer method describedhereafter, or a nozzle-injection method (application may also beperformed using the device used to screen print the phosphor layer,illustrated in FIG. 2). Of these methods, the nozzle-injection methodcan be used to apply the bonding agent Bd most accurately to theindentation 504, and so is the preferred method.

[0269] Finally, this structure is fired, forming barrier rib and bondingagent layers, the layer of bonding agent being arranged evenly acrossthe barrier rib tops 18 a. In addition, the bonding agent Bd is sunkinto the indentations 504, so that the degree of bonding agent seepageinto the cell area after the PDP is completed is less that ifindentations 504 are not formed. To reduce the amount of bonding agentseepage into the cell area still further, the indentations 504 should beformed along the central part of each barrier rib 18. The reason forthis is that the central part of the barrier rib 18 is the part furthestfrom the cells.

[0270] Note that the bonding agent coating may be performed eitherbefore or after the phosphor layer is formed between the barrier ribs.

[0271] Thirteenth Embodiment

[0272] This embodiment is characterized by a metal mold used in a methodfor arranging the bonding agent on the tops of the barrier ribs, as inthe eleventh embodiment, so the following explanation concentrates onthis metal mold.

[0273] In the present embodiment, the metal mold has a unique shape, asillustrated in FIG. 24. This metal mold 601 is shaped so that an evenindentation 604 is formed along the length of the bottom part 603 ofeach of the troughs 602 which make up the pattern for the barrier ribs18.

[0274]FIG. 25 shows the process for obtaining a structure formed fromthe barrier ribs and the bonding agent using the metal mold 601.

[0275] First, as shown in FIG. 25, stage (1), a base plate 606 is pusheddown on a metal mold 601 sandwiching a green sheet 605 in between. Abonding paste 604 a has already been injected into the indentations 604a in the metal mold 601 using the nozzle-injection method. The amount ofbonding agent Bd applied is determined by the size of the indentations604 a. In view of the need to reduce the amount of bonding agent seepageinto the cell area following the completion of the PDP, however, theindentations 604 a should be of the smallest possible size that willachieve this while still preserving sufficient bonding strength. Theindentations 604 a should also be located along the central part of thebarrier ribs 18, as was explained previously.

[0276] Following this, in stage (2), the base plate 606 is pushed downon to the metal mold 601 while being heated, so a structure formed fromlaminated barrier ribs 18 and bonding agent Bd can be obtained. Thismethod determines the locations of the barrier ribs 18 and the bondingagent Bd, so that the bonding agent Bd can be arranged accurately on thebarrier ribs 18.

[0277] Next, in stage (3), the base plate 606 is separated from themetal mold 601, transferring the above-mentioned structure to the baseplate 606.

[0278] Finally, this structure is fired, forming barrier rib and bondingagent layers, the layer of bonding agent being arranged evenly along thebarrier rib tops.

[0279] Fourteenth Embodiment

[0280] This embodiment is characterized by a method for arranging thebonding agent on the tops of the barrier ribs, so the followingexplanation concentrates on this method.

[0281]FIG. 26 is a process diagram showing a method for arranging thebonding agent in the present embodiment. The processing sequence isperformed in the order of the stages (1) to (4).

[0282] First, in stage (1), a back substrate PA2, in which addresselectrodes 16, the visible light reflecting layer 17 and barrier ribs 18are formed on a back glass plate 15 is prepared (a phosphor layer may beformed at this stage or later). A resinous film 701 is applied on top ofthe barrier ribs 18. The resinous film 701 is made from a layer ofthermohardening resin 701 a (for example epoxy resin) closest to theback substrate PA2, on which is placed a resinous film 701 b (PET resinor similar). The resinous film 701 is pressed against the back substratePA2 while being heated, so that the layer of thermohardening resin 701 ahardens and is fixed to the surface of the barrier ribs 18.

[0283] Following this, in stage (2), apertures 703 are cut in theresinous film 701 at various points located along the tops 18 a of thebarrier ribs 18 by concentrating a laser beam 702 on the tops of thebarrier ribs and scanning the laser beam 702 along the length of eachbarrier rib 18. This laser irradiation is performed by a device like theone shown in FIG. 26, stage (2). In the device shown here, alight-focusing lens 704 can be moved freely across a plane such that theoptical axis is parallel to the light-receiving object (the backsubstrate PA2). Then, a laser beam 702 is guided from a laser beamgenerator 705 via optical fibers onto the light-focusing lens 704. Thelaser beam generator 705 emits light using yttrium aluminum garnet(YAG), and outputs the laser beam 702 in pulses. Before the laser beam702 is scanned across the surface of the back substrate PA2, the shapeof the barrier ribs is monitored using a probe light 706 and a detector707. A control unit 708 uses the result of the monitoring to control thescan direction and strength of the laser beam 702, so that the apertures703 can be established along the tops of the barrier ribs 18. Theapertures 703 can also be established so as to correspond to the shapeof the barrier ribs 18 by using this method. In this case, however, thelight from the probe light 706 needs to be able to pass through theresinous film, so the resinous film 701 should have a high degree oftransparency. Alternatively, the tops of the barrier ribs 18 may becoated with a black pigment which easily absorbs laser light. The laserbeam 702 is absorbed by this pigment, enabling the apertures 703 to beestablished along the tops of the barrier ribs 18 with greater accuracy.

[0284] The amount of bonding agent applied is determined by the size ofthe apertures 703. In view of the need to reduce the amount of bondingagent seepage into the cell area following the completion of the PDP,however, the apertures 703 should be of the smallest possible size thatwill achieve this while still preserving sufficient bonding strength.The apertures 703 should also be located along the central part of eachbarrier rib 18 to further reduce the risk of seepage.

[0285] Next, in stage (3), a bonding agent 709 is applied to theopenings 703 using a squeegee 710. Note that when the bonding agent 709is applied, it is vital to ensure that the resinous film 701 remains inthe same location relative to the back substrate PA2.

[0286] Following this, in stage (4), bonding agent 709 adhering to thesurface of the resinous film 701 is removed using a tape polishingmethod. Then, the remaining resinous film 701 is removed using a methodsuch as peeling off the film, melting or sublimation by a laser beam.Thus, a layer of bonding agent 709 can be formed evenly along the topsof the barrier ribs 18.

[0287] A photoresist method may be used as an alternative method forestablishing apertures in a film to apply the bonding agent selectivelyto the tops of the barrier ribs 18.

[0288] Fifteenth Embodiment

[0289] This embodiment is characterized by a method for arranging thebonding agent on the tops of the barrier ribs, so the followingexplanation concentrates on this method.

[0290]FIG. 27 is a process diagram showing the method for arranging thebonding agent in the present embodiment. The processing sequence isperformed in the order of the stages (1) to (4). As shown in thesedrawings, the bonding agent in the present embodiment is arranged on thebarrier ribs using the film transfer method described below.

[0291] First, in stage (1), a back substrate PA2, formed by arrangingthe visible light-reflecting layer 17 and barrier ribs 18 on a backglass plate 15, is prepared (the phosphor layer 19 may be formed at thisstage or later).

[0292] Next, in stage (2), a transfer film 801 is arranged on top of thebarrier ribs 18 so that the barrier ribs 18 and the transfer film 801are touching.

[0293] The transfer film 801 is made of a layer of resinous film 801 a,such as PET resin, to which a bonding agent layer 801 b is applied,using a printing method such as screen-printing or a doctor blade, andthen dried. The transfer film 801 is arranged on the back substrate PA2so that the bonding agent layer 801 b is in contact with the barrierribs 18.

[0294] Following this, in stage (3), a pair of rollers 802 arepositioned sandwiching the layered substances, and rolled across theupper surface of the resinous film 801 a bringing an equal load to bearacross the whole of the back substrate PA2. As a result of this, thebonding agent layer 801 b is loosened from the resinous film 801 a andattached to the tops of the barrier ribs 18.

[0295] Next, in stage (4), the transfer film 801 is peeled off from thesubstrate PA2 leaving the bonding agent 803 arranged evenly along thetops of the barrier ribs.

[0296] The bonding agent 803 which has not been transferred to the topsof the barrier ribs 18 needs to be removed as cleanly as possible. Thepreferred method for separating the transfer film 801 from the backsubstrate PA2 should be as shown in FIG. 28 or 29.

[0297] The method shown in FIG. 28 is as follows. In stage (1), only theresinous film 801 a is peeled off. Next, in stage (2), an adhesive film804 having an appropriate degree of adhesiveness (for example Hitalexfilm, produced by Hitachi Chemical Corp) is attached to the uppersurface of the bonding agent layer 801 b. Following this, in stage (3),the adhesive film 804 is lifted up, attaching the bonding agent layer801 b to the tops of the barrier ribs 18 while simultaneously peelingoff the unnecessary parts.

[0298] In the method shown in FIG. 29, a double-sided adhesive film 805has already been placed between the resinous film 801 a and the bondingagent layer 801 b forming the transfer film 801. In this method, theprocess in which the resinous film is peeled off before the adhesivefilm is applied is omitted, simplifying the process for arranging thebonding agent.

[0299] Note that it is preferable if the back substrate PA2 is heatedwhile the bonding agent 803 is transferred, since this enables thebonding agent 803 to be transferred with greater accuracy. The heatingmethod may involve heating the surface of the roller 802 that passesacross the surface of the back substrate PA2. Alternatively, the bondingagent 803 may be more accurately transferred to the tops of the barrierribs 18 if pressure generated when the transfer film 801 is pressed ontothe barrier ribs 18 is cushioned by a material placed between thetransfer film 801 and the barrier ribs 18.

[0300] If a coating of a flexible substance is used as this cushioningmaterial, the bonding agent 803 can be transferred to the tops of thebarrier ribs 18 even more accurately. This is due to thepreviously-explained variations in the heights of the barrier ribs 18.If a coating of a non-flexible substance is used, the bonding agent 803will not be arranged on the lower barrier rib tops 18 a. Should aflexible coating be used, however, the bonding agent 803 can be evenlyarranged on each barrier rib 18, without the variations in height havingany influence.

[0301] Sixteenth Embodiment

[0302] This embodiment is characterized by a method for arranging thebonding agent on the tops of the barrier ribs, so the followingexplanation concentrates on this method.

[0303]FIG. 30 is a process diagram showing the method for arranging thebonding agent in the present embodiment. The processing is performed inthe order of the stages (1) to (5).

[0304] First, in stage (1), a back substrate PA2, formed by arrangingthe visible light reflecting layer 17 and barrier ribs 18 on the backglass plate 15, is prepared (the phosphor layer 19 may be formed at thisstage or later).

[0305] Following this, in stage (2), a screen plate 901 is arranged ontop of the barrier ribs 18. The screen plate 901 has apertures 901 aplaced in the same pattern as the barrier ribs 18, each aperture 901 abeing slightly wider than the top of a barrier rib 18.

[0306] Next, in stage (3), a squeegee 902 is used to spread a bondingagent 903 over the tops of the barrier ribs 18, so that the bondingagent layer 907 is slightly wider than the width of the barrier rib 18.The squeegee 902 may be made of urethane resin. The bonding agent 903 isthen dried at a specified temperature of around 80° C. to 120° C. Here,the paste used for the bonding agent 903 is a composite including anacrylic resin that hardens when exposed to ultraviolet light, glass fritand various other solvents and resins.

[0307] In stage (4), a photo mask 905, in which apertures 904 have beenformed in a specific pattern, is placed above the back substrate PA2.Then the bonding agent 903 located on the tops of the barrier ribs 18 isexposed to an ultraviolet light 906 with an intensity of, for example,500 mJ/cm². The part of the bonding agent 903 exposed to the ultravioletlight 906 hardens due to the reaction of the acrylic resin that hardenswhen exposed to ultraviolet light, while the part of the bonding agent903 which is not exposed to ultraviolet light remains soft. The amountof bonding agent 903 applied is determined by the size of the areaexposed to ultraviolet light. In view of the need to reduce the amountof bonding agent seepage into the cell area following the completion ofthe PDP, however, the area exposed should preferably be narrower thanthe width of the tops of the barrier ribs W1 and located along thecentral part of the area 907 on the tops of the barrier ribs 18.

[0308] Here, heating the hardened bonding agent 903 to strengthen itstill further is preferable.

[0309] Next, in stage (5), the soft areas of the bonding agent 903 areremoved. This is performed by spraying with a liquid developer todevelop the soft areas. The liquid developer may be at room temperature,but the developing will be performed more effectively if it is heated toa temperature of around 40° C. to 60° C. An alkaline solution such assodium hydroxide solution or sodium carbonate solution may be used asthe liquid developer.

[0310] The above process enables the bonding agent 903 to be arranged ona narrow area on the tops of the barrier ribs 18. Note that if theaperture pattern is formed in the screen plate according to the shape ofthe barrier ribs 18, as in stage (2), the bonding agent 903 can beapplied lengthwise along the barrier ribs 18.

[0311] Seventeenth Embodiment

[0312] This embodiment is characterized by a method for applying thebonding agent to the tops of the barrier ribs before exposing it toultraviolet light, as was shown in stage (3), so the followingexplanation concentrates on this method.

[0313]FIG. 31 is a process diagram showing the method for arranging thebonding agent in the present embodiment. This drawing shows an identicalprocess to that shown in FIG. 30, stage (2).

[0314] As shown in the drawing, the bonding agent is arranged on thetops of the barrier ribs by fixing a bonding agent sheet 1001, alreadyformed from the previously described paste composite, on the barrierribs 18. This may be performed using a pair of pressure rollers 1002.The back panel PA2 and the pressure rollers 1002 should also be heatedduring the fixing process in order to improve cohesiveness.

[0315] The embodiments thus far have described methods of arranging thebonding agent. At this point therefore it would seem appropriate to givea brief indication of the degree of bonding strength possessed by a PDPmanufactured using the methods described in the first to seventeenthembodiments.

[0316] The inside of a PDP manufactured based on the above embodimentswas pressurized by the introduction of air, and the bonding strengthdetermined by the pressure value obtained at the time the panelexploded. The resulting value was found to be 6100 torr.

[0317] Eighteenth Embodiment

[0318] This embodiment is characterized by the bonding agent itself, sothe following explanation concentrates on the composition of the bondingagent.

[0319] In the present embodiment, the bonding agent applied to the topsof the barrier ribs is a mixture including beads having a higher meltingpoint than that of the glass substance used to fix the barrier ribs andthe protective layer together. Attachment is performed at a temperaturebetween the melting points of the beads and the glass substance, so thatthe latter melts, but the former does not. The following effects areachieved by performing attachment at this temperature using such abonding agent.

[0320]FIG. 32 shows two examples of the situation occurring when thetops of the barrier ribs 18 are attached to the protective layer usingthe bonding agent. FIG. 32A shows the situation when a bonding agentcontaining beads as described in the present embodiment is used. FIG.32B shows the situation when a bonding agent that does not use thesebeads is employed.

[0321] When beads 1012 are not used, as shown in FIG. 32B, the meltedglass substance 1011 is pressed downward by the weight of the frontsubstrate PA1 during attachment. As a result, the panel is fired withthe glass substance 1011 having seeped into the cell area. If beads 1012are used, however, as shown in FIG. 30A, the weight of the frontsubstrate PA1 is borne by the beads 1012, preventing the melted glasssubstance 1011 from seeping into the cell area.

[0322] The ability of the beads 1012 to prevent the melted glasssubstance 1011 from seeping into the cell area is greater if theparticle diameter of the beads 1012 is larger, and even more marked ifthe particle diameter of the beads 1012 is greater than the particlediameter of the glass substance 1011. The reason for prescribing theparticle diameter of the beads 1012 in this way is that the quantity ofglass substance 1011 pressed down by the front panel PA1 will be reducedfurther.

[0323] The beads 1012 may be formed from the simple substances aluminumoxide (Al₂O₃) or silicon oxide (SiO₂), or from compounds containingthese substances.

[0324] Here, the method for arranging the bonding agent may be any oneof the methods described in the preceding first to seventeenthembodiments. However, if the method used is that described in any one ofthe first through seventh, twelfth and thirteenth embodiments theresults will be more effective. This is because the method described inthe first to seventh embodiments applies the bonding agent to the topsof the barrier ribs in such a way as to reduce the amount of seepageinto the cell areas, and use of this in combination with the beadsreduces the amount of seepage still further. The method described in thetwelfth and thirteenth embodiments. sinks the bonding agent intoindentations in the tops of the barrier ribs, and use of this incombination with the beads also reduces the amount of seepage stillfurther.

[0325] Nineteenth Embodiment

[0326] The PDP in this embodiment is realized by a structure in whichdischarge inside the panel mainly occurs in areas distanced from thesection where the barrier ribs are connected to the front substrate PA1.

[0327]FIG. 33 is a top view showing the positional relationship betweenthe matrix formed by the discharge electrodes 12 and the top surfaces 18a of the barrier ribs coated with the bonding agent Bd.

[0328] As shown in the diagram, transparent electrodes 12 a (shown bythe diagonally-shaded areas in the drawing) are disposed in stripes witha gap G1 (a discharge gap) on one side of each transparent electrode 12a and a gap G1 (a dividing gap) on the other. The transparent electrodes12 a are formed on either side of the gaps G1, with protrusions 12 aformed at uniform intervals of distance d3 along the main lines 12 a 2.Metal electrodes 12 b are formed on the surface of the main lines 12 a 2as virtually straight lines. The gaps G1 have a width of distance d1,this being the width between two facing protrusions 12 a 1. The gaps G1have a width d2 which is wider than the width of gaps G1. Dischargeoccurs in the narrow gaps of the width d1 formed between the pairs offacing protrusions 12 a 1. The electrodes are separated by the wide gapsG1 of the width d2 to prevent crosstalk.

[0329] The top surfaces 18 a of the barrier ribs 18 on which the bondingagent Bd has been applied are connected to part of the protective layerand thence to the dielectric glass layer. When the surface of the PDP isviewed from above, this part of the dielectric glass layer correspondsto the areas (indentations 12 a 3) between the protrusions 12 a. Thebarrier ribs are attached to the central area of each sequence ofindentations 12 a 3, so that the edges of the barrier ribs are located adistance of d4from the sides 12 a 11 of the protrusions 12 a on eitherside. Here, the top surfaces 18 a of the barrier ribs 18 are describedas being located so that the discharge spaces 20 on either side are anequal distance d4 away. As long as the effects explained below can stillbe obtained, however, the distances on the left and right sides need notbe equal. The same applies to the relative location of the top surfacesof the barrier ribs 18 to other elements explained in the followingembodiments.

[0330] The following functions and effects may be obtained due to theabove shape of the transparent electrodes 12 a and the positionalrelationship between the top surfaces of the barrier ribs 18 coated withthe bonding agent Bd and the transparent electrodes 12 a.

[0331] First, the conditions while discharge is in progress areexplained. In the initial stage of the application of a dischargesustain voltage to the transparent electrodes 12 a, discharge starts inthe gaps of width dl between the opposing protrusions 12 a 1 belongingto different lines of electrodes. The reason for this is that a strongelectric field is generated in the places where transparent electrodes12 a are close to one another, so that discharge is easily started. Thedischarge surface then spreads out towards the main lines of thetransparent electrodes 12 a.

[0332] Even if the discharge surface spreads in this fashion, however,discharge mainly occurs between the opposing protrusions 12 a 1belonging to different lines of electrodes, rarely spreading as far asthe indentations 12 a 3. This is because the electric field is weakerwhere the electrodes are spaced further apart.

[0333] Since discharge mainly occurs between the opposing protrusions 12a 1 belonging to different lines of electrodes, it mainly occurs at alocation separated from the bonding agent applied to the top surfaces ofthe barrier ribs 18 by a horizontal distance equivalent to d4.

[0334] Accordingly, the bonding agent Bd applied to the top surfaces ofthe barrier ribs 18 is less likely to be exposed to discharge,preventing pigments, residual carbon and the like from contaminating thedischarge gas in the discharge spaces 20. As a result, increases indischarge voltage, decreases in discharge efficiency, deterioration ofthe phosphors and reduction in luminance are less likely, and initialoperating performance can be sustained over the long term.

[0335] The following is an explanation of part of the manufacturingmethod for a PDP constructed as in the present embodiment. This partdiffers from the manufacturing methods described in the previousembodiments.

[0336] The transparent electrodes 12 a are formed on the surface of theback glass plate 11 in a shape having the above indentations andprotrusions using a photolithograph or laser application method. Then,the metal electrodes 12 b are formed on the transparent electrodes 12 ausing a photolithograph method.

[0337] Next, the front substrate PA1 and the back substrate PA2 arefixed together by firing after the barrier ribs 18, on which the bondingagent Bd has been applied, have been correctly aligned with the surfaceof the protective layer 14 on the front panel PA1 and the barrier ribs18 and the front panel PA1 pushed together.

[0338] The following is a detailed explanation of the method for formingthe discharge electrodes 12.

[0339] Firstly, a formation method using lithographing techniques isexplained. A transparent conductive film made of a metal oxide film,such as a layer of ITO or SnO₂, is formed on the front glass layer 11using a sputter method. After this, a photoresist layer is formed on topof the metal oxide film. Lines of electrodes having the aboveindentations and protrusions are formed using photolithography by usinga mask to expose only part of the surface to light rays.

[0340] Next, a simple explanation of the laser application method isgiven. FIG. 34 is an outline drawing of a laser processing device 1020for performing the laser application method.

[0341] In the device shown in FIG. 34, a light-focusing lens 1021 can bedriven so that it moves freely with an optical axis on a plane parallelto the light-receiving object (the front glass plate 11). Laser light1022 is guided from a laser generator 1022 onto the light-focusing lens1021 via optical fibers. The laser generator 1022 emits light using YAGand outputs the laser light 1023 in pulses (the laser pulse repetitionrate is, for example, 5000 PPS). The laser light 1023 is passed throughan aperture 1024 to focus it on the surface of the metal oxide film1025, forming a small spot 1026. The laser spot 1026 is, for example, arectangle of a specific size, formed by a pulse width of 100 nanosecondsand a wavelength of 1.06 μm, with each pulse having an intensity of 1.5mJ/cm². The size of the laser spot 1026 is determined by adjusting thedimensions of the aperture 1024 and distance of the light-focusing lens1021 from the light-receiving body as appropriate.

[0342] The pattern for the transparent electrodes 12 a can be formedusing this laser processing device 1020 by aiming a laser at the surfaceof a metal oxide film 1025 (transparent conductive film) already formedon the front glass plate 11 by the sputter method, and then scanning thelaser across the surface of this metal oxide film 1025 to remove partsunnecessary for the pattern.

[0343] Note that the indentations and protrusions in the transparentelectrodes 12 a may be of a semi-circular or triangular shape, insteadof the rectangular shape shown here.

[0344] Twentieth Embodiment

[0345] The PDP in this embodiment is characterized by the shape of thetransparent electrodes, so the following explanation concentrates onthis point.

[0346]FIG. 35 shows the shape of transparent electrodes 1030 and thepositional relationship of these transparent electrodes 1030 and thebarrier ribs 18 to which the bonding agent Bd has been applied in thepresent embodiment.

[0347] As shown in the drawing, the main electrodes lines 12 a 2, whichlinked neighboring protrusions 12 a 1 in each electrode in thenineteenth embodiment, have been removed here. Instead, transparentelectrodes 1030, each of which is an isolated rectangle, are placed in astraight line a uniform distance apart. The transparent electrodes 1030are electrically connected by metal electrodes 1031 constructed on theirsurface.

[0348] The top surfaces of the barrier ribs 18, to which the bondingagent Bd has been applied, are located running between pairs of adjacenttransparent electrodes 1030 a belonging to the same electrode lines. Thebarrier ribs 18 are attached via the protective layer to the parts ofthe dielectric glass layer that are separated from the transparentelectrodes 1030 a on either side by a distance d5.

[0349] By determining the formation of the transparent electrodes 1030and the positional relationship of the transparent electrodes 1030 andthe barrier ribs 18 in this way, discharge occurs mainly in the spacesbetween facing transparent electrodes 1030. Thus, discharge mainlyoccurs at positions that are a horizontal distance equivalent to d5 fromthe top surfaces of the barrier ribs to which bonding agent Bd has beenapplied.

[0350] Accordingly, the bonding agent Bd applied to the top surfaces ofthe barrier ribs 18 is less likely to be exposed to discharge,preventing pigments, residual carbon and the like from contaminating thedischarge gas in the discharge spaces 20. As a result, increases indischarge voltage, decreases in discharge efficiency, deterioration ofthe phosphors and reduction in luminance are less likely, and initialoperating performance can be sustained over the long term.

[0351] Twenty-First Embodiment

[0352] The PDP in the present embodiment is characterized by a patternformed by the protective layer, so the following focuses on anexplanation of this pattern.

[0353] Here, each transparent electrode is a conventional straightelectrode line, without the indentations and protrusions of thenineteenth embodiment.

[0354]FIG. 36 shows the pattern formed by the protective layer, and thepositional relationship of the protective layer and the top surfaces ofthe barrier ribs on which the bonding agent Bd has been applied, in thepresent embodiment.

[0355] A protective layer 1040 in the present embodiment is formed onparts of the surface of a dielectric glass layer, rather than coveringthe whole surface of the dielectric glass layer, as was the case in thenineteenth embodiment. In other words, the protective layer 1040 in thepresent embodiment, as shown in FIG. 36, is formed from a plurality oflong narrow strips 1040 a placed at set intervals.

[0356] The strips 1040 a run in the same direction as the addresselectrodes 16 on the back substrate PA2, and are located above theaddress electrodes 16, at a distance d7 from the top surfaces 18 a ofthe barrier ribs 18.

[0357] By determining the formation of the pattern for the protectivelayer 1040 and the positional relationship of the protective layer 1040and the barrier ribs 18 in this way, discharge mainly occurs in spacesseparated horizontally from the top surfaces of the barrier ribs 18 towhich bonding agent Bd has been applied by a distance equivalent to d7,as was the case in the nineteenth embodiment.

[0358] The reason for this is that secondary electrons are more likelyto be released from the surface of the protective layer made of MgO thanfrom the dielectric glass layer. A value called the secondary electronrelease coefficient γ (hereafter referred to as the coefficient γ)expresses the degree of ease with which secondary electrons are releasedas a numeric value. Since the coefficient γ for the protective layermade of MgO is higher than that for the dielectric glass layer, an MgOfilm is conventionally formed on the surface of the dielectric glasslayer to promote the occurrence of discharge. A description of thistechnique may be found in issue No. 167 of the journal Thin Solid Films,pages 299 to 308 (pub. 1988).

[0359] Secondary electrons are mainly released from the surface of theMgO strips 1040 a, where the coefficient γ is higher. As a result,discharge mainly occurs in the discharge spaces 20 beneath the surfaceof the strips 1040 a.

[0360] Accordingly, the bonding agent Bd applied to the top surfaces ofthe barrier ribs 18 is less likely to be exposed to discharge,preventing pigments, residual carbon, and the like from contaminatingthe discharge gas in the discharge spaces 20. As a result, increases indischarge voltage, decreases in discharge efficiency, deterioration ofthe phosphors and reduction in luminance are less likely, and initialoperating performance can be sustained over the long term.

[0361] Note that the protective layer 1040 arranged in strips as aboveis formed as in the nineteenth embodiment. In other words, a thin filmof MgO is formed over the entire surface of the dielectric glass layerusing a CVD (chemical vapor deposition) method, and a specific patternis then formed using a method such as photolithography.

[0362] Twenty-Second Embodiment

[0363] The PDP in the present embodiment is characterized by thecross-sectional shape of the dielectric glass layer formed on the frontsubstrate PA1, so the following explanation concentrates on thiscross-sectional shape.

[0364] Here, each transparent electrode is a conventional straightelectrode line, without the indentations and protrusions of thenineteenth embodiment.

[0365]FIG. 37 shows the cross-sectional shape of a dielectric glasslayer 1050 and the positional relationship of the dielectric glass layer1050 and the barrier ribs 18 on which the bonding agent Bd has beenapplied, in the present embodiment.

[0366] In the nineteenth embodiment, the dielectric glass layer formedon the front substrate PA1 was of virtually the same thickness acrossits entire surface. In the present embodiment, however, the thickness ofthe dielectric glass layer 1050 is varied at uniform intervals, as shownin FIG. 37.

[0367] This means that thin film sections 1050 a with a thickness of d8and a width of d9 are alternated with thick film sections 1050 b with athickness of d10 and a width of d11 in a stripe formation. Then thebarrier ribs 18 are connected to the protective layer almost directlybeneath the central part of the thick film sections 1050 b, using thebonding agent Bd. The thin film sections 1050 a border the top centralpart of each discharge space 20, at a distance of d12 from the topsurfaces 18 a of the barrier ribs 18.

[0368] By determining the cross-sectional formation of the dielectricglass layer 1050 arranged on the front substrate PA1 and the positionalrelationship of the dielectric glass 1050 layer and the barrier ribs 18in this way, discharge mainly occurs in spaces separated horizontallyfrom the top surfaces of the barrier ribs 18 to which bonding agent Bdhas been applied by a distance equivalent to d12, as was also the casein the nineteenth embodiment.

[0369] In other words, the charge accumulated on the dielectric glasslayer 1050 is greater where the layer is thinner. As a result, dischargeoccurs mainly in the parts of the discharge spaces 20 beneath thesurface of the protective layer covering the thin film sections 1050 aof the dielectric glass layer 1050.

[0370] Accordingly, the bonding agent Bd applied to the top surfaces ofthe barrier ribs 18 is less likely to be exposed to discharge,preventing pigments, residual carbon, and the like from contaminatingthe discharge gas in the discharge spaces 20. As a result, increases indischarge voltage, decreases in discharge efficiency, deterioration ofthe phosphors and reduction in luminance are less likely, and initialoperating performance can be sustained over the long term.

[0371] The difference in thickness between the thin film sections 1050 aand the thick film sections 1050 b should be of around 5 to 10 μm.

[0372] The above-mentioned dielectric glass layer 1050 may be formed byusing a coating method such as screen-printing, dye coating,spraying-coating or plate-coating to apply a uniform coat of a pastecontaining dielectric glass. Then the paste is further applied atuniform intervals in a stripe formation, and the result fired, to form adielectric glass layer having indentations and protrusions having thevariations in thickness described above.

[0373] Instead of varying the thickness of the dielectric glass layer asdescribed above, the thickness of the protective layer attached to thesurface of the dielectric glass layer may be varied using the samepattern. If differences in thickness are created in the protective layerin this way, secondary electrons will mainly be released from thethinner parts of the protective layer. As a result, discharge mainlyoccurs in spaces separated horizontally by a certain distance from thetop surfaces of the barrier ribs to which bonding agent has beenapplied.

[0374] Twenty-Third Embodiment

[0375] The PDP in this embodiment is characterized by a pattern formedby the protective layer, so the following explanation concentrates onthis pattern.

[0376] Here, each transparent electrode is a conventional straightelectrode line, without the indentations and protrusions of thenineteenth embodiment.

[0377]FIG. 38 shows a pattern formed by a protective layer 1060 and thepositional relationship of the protective layer 1060 and the barrierribs to which the bonding agent Bd was applied, in the presentembodiment.

[0378] In the nineteenth embodiment, the roughness of the protectivelayer on the front substrate PA1 was virtually identical across itsentire surface. In the present embodiment, however, as shown in FIG. 38,the roughness of the protective layer 1060 is varied at uniformintervals.

[0379] This means that the surface of the protective layer 1060bordering the discharge spaces 20 is formed from alternating stripes1060 a and 1060 b having different roughnesses. The areas 1060 a (shadedin the drawing) have a width of d13 and a roughness f1 and the areas1060 b have a width of d14 and a roughness f2. The surface roughness ofthe areas 1060 a is greater than that of 1060 b. The barrier ribs 18 areconnected to the central surface of the areas 1060 b using the bondingagent Bd, and the areas 1060 a are separated by a distance of d15 fromthe top surfaces of the barrier ribs 18 and border on the upper centralpart of each discharge space 20.

[0380] By determining the surface roughness of the protective layer 1060arranged on the front substrate PA1 and the positional relationship ofthe protective layer 1060 and the barrier ribs 18 in this way, dischargemainly occurs in spaces separated horizontally from the top surfaces ofthe barrier ribs 18 to which bonding agent Bd has been applied by adistance equivalent to d15, as was also the case in the nineteenthembodiment.

[0381] This means that secondary electrons will mainly be released fromthe areas 1060 a where the surface of the protective layer 1060 isrougher. As a result, discharge mainly occurs in the areas of thedischarge spaces 20 between the areas 1060 a. The reason that secondaryelectrons are mainly released from the areas 1060 a is that the rougherareas have a larger surface area available to release secondaryelectrons, so that the coefficient γ is greater in those areas.

[0382] Accordingly, the bonding agent Bd applied to the top surfaces ofthe barrier ribs 18 is less likely to be exposed to discharge,preventing pigments, residual carbon, and the like from contaminatingthe discharge gas in the discharge spaces 20. As a result, increases indischarge voltage, decreases in discharge efficiency, deterioration ofthe phosphors and reduction in luminance are less likely, and initialoperating performance can be sustained over the long term.

[0383] The difference in roughness between the areas 1060 a and 1060 bshould preferably be of around 10 to 100 angstroms (average roughness ofthe center line).

[0384] The above-described protective layer 1060 may also be formed inthe following way. First, an even MgO film is formed using a CVD method.Then, specified sections of the protective layer 1060 only may be etchedby a method such as sputtering, performed by exposing the surface of theprotective layer 1060 to plasma after it has been covered by a mask.This causes portions of the surface to become rougher.

[0385] Twenty-fourth Embodiment

[0386] The PDP in this embodiment is characterized by the parts wherethe bonding agent and the front substrate connect, so the followingexplanation concentrates on these connecting parts.

[0387]FIG. 39 is an aerial view of the structure of the PDP in thepresent embodiment. This drawing shows the positional relationship ofthe parts connected with the front substrate and the cells (the cellsbeing the points where the discharge electrodes and the addresselectrodes intersect).

[0388] As shown in the drawing, the top surfaces of the barrier ribs1070 are connected to the front substrate PA1 excluding those areas onwhich the cells C1, C2, C3 etc.(shown by the bold lines in the drawing)are constructed, in other words, the shaded sections 1070 in thedrawing.

[0389] Accordingly, the bonding agent Bd applied to the top surfaces ofthe barrier ribs 18 is less likely to be exposed to discharge,preventing pigments, residual carbon and the like from contaminating thedischarge gas in the discharge spaces 20. As a result, increases indischarge voltage, decreases in discharge efficiency, deterioration ofthe phosphors and reduction in luminance are less likely, and initialoperating performance can be sustained over the long term.

[0390] This kind of connection can be simply performed by applying thebonding agent Bd to the top surfaces of the barrier ribs 18 at uniformintervals using, for example, a screen-printing method.

[0391] A panel structure that differs from those described in thenineteenth to twenty-fourth embodiments may be used, with the bondingagent arranged on the barrier rib tops so that the area covered isnarrower than the width of the upper surface of each barrier rib. Inthis case, the bonding agent does not ooze out when connection isperformed, and pigments, residual carbon and the like can be preventedfrom contaminating the discharge gas in the discharge spaces.Prescribing the width of the applied bonding agent in this way alsoincreases the cell area, enabling improved luminance to be realized.

[0392] Experiment

[0393] The changes in luminance shown when a PDP manufactured based onthe nineteenth embodiment was driven continuously are shown by themedian line 1 in FIG. 40. The changes in luminance shown when a PDP withconventional straight transparent electrodes was also drivencontinuously, as a comparative example, are shown by the median line 2in FIG. 40.

[0394] As can be clearly seen from these results, the luminance in thecomparative PDP dropped dramatically after discharge had taken place fora number of hours. In contrast, the luminance for the PDP manufacturedbased on the nineteenth embodiment exhibited almost no change.

[0395] The reason for this is that the PDP of the nineteenth embodimenteffectively prevents changes in the properties of the bonding agent.

[0396] Note that in the first to eighteenth embodiments the front andback substrates may be connected using a conventional method such assoftening the bonding agent, but connection may also be performed bysoftening the parts of the front and back substrates touching thebonding agent, rather than the bonding agent itself. In the former case,the bonding agent should have a lower softening point (or melting point)than the parts of the front and back substrates touching the bondingagent. In the latter case, the parts of the front and back substratestouching the bonding agent should have a lower softening point (ormelting point) than the bonding agent.

[0397] The nineteenth to twenty-fourth embodiments use MgO as theprotective layer, but MgF₂ or MgO_(x) (x<1) may also be used.

[0398] In addition, in the first to eighteenth embodiments the barrierribs were described as being placed in a stripe formation, but thebarrier ribs may also be arranged in other formations.

[0399] The explanation in the first to eighteenth embodiments focused onthe use of the invention in a gas display panel, but the same methodsmay also be used in other display panels, such as FED (field emissiondisplay) panels, provided that the panel concerned is formed from a pairof substrates, arranged in opposition and sealed together at theperimeter, on at least one of which barrier ribs are formed.

[0400] Industrial Applicability

[0401] The display panel manufacturing method of the present inventionmay be used in the manufacture of display panels used for image displayin televisions, computer monitors and the like.

1. A display panel manufacturing method, comprising an applicationprocess for applying a bonding agent to a plurality of barrier ribsformed on at least one of a pair of substrates, and a connection processfor arranging the pair of substrates in opposition and connecting thepair of substrates together via the bonding agent that has been appliedto the barrier ribs, wherein the application process includes: a bondingagent holding process for having a bond holding member hold a paste-likebond to form a surface; and a bonding agent applying process forapplying the bonding agent to almost an entire top surface of eachbarrier rib by bringing virtually the entire top surface of each barrierrib into contact with the bonding agent layer, while regulating a degreeof contact between the bonding agent layer and the barrier ribs.
 2. Thedisplay panel manufacturing process of claim 1, wherein the bondingagent applying process includes: a first step for arranging thesubstrate on which the barrier ribs are formed and the bonding agent inopposition, with a gap between the barrier rib tops and the bondingagent; and a second step for regulating the degree of contact betweenthe barrier rib tops and the bonding agent by controlling the distancebetween the barrier ribs and the bonding agent.
 3. The display panelmanufacturing method of claim 1, wherein the bonding agent applyingprocess includes: a third step for placing the substrate on which thebarrier ribs are formed and the bonding agent in opposition, with a gapbetween the barrier rib tops and the bonding agent; a fourth step forbringing one part of each barrier rib into contact with the bondingagent by controlling the distance between the barrier ribs and thebonding agent to a distance at which the bonding agent is applied to thebarrier rib tops as a result of surface tension; and a fifth step forbringing the surface of the bonding agent and virtually the entiresurface of each barrier rib top into contact by altering the relativepositions of the bonding agent and the barrier ribs while maintainingthe distance between the barrier ribs and the bonding agent to adistance at which the bonding agent continues to be applied to thebarrier ribs as a result of continuing surface tension.
 4. The displaypanel manufacturing method of claim 1, wherein the bonding agentapplying process further comprises: a sixth step for placing thesubstrate on which the barrier ribs are formed, and the bonding agent inopposition, with a gap between the barrier rib tops and the bondingagent; and a seventh step for bringing the barrier ribs into contactwith the bonding agent using a regulating means for regulating theposition of the barrier rib tops in relation to the bonding agent. 5.The display panel manufacturing method of claim 4, wherein the bondingagent applying process further includes: an eighth step for altering therelative positions of the bonding agent and the barrier ribs with thebarrier rib tops in contact with the regulating means.
 6. The displaypanel manufacturing method of claim 4, wherein the bonding agent holdingmember is a rotating object on whose surface the bonding agent is held;and the bonding agent applying process includes a ninth step forbringing the bonding agent into contact with virtually the entiresurface of the barrier rib tops by rotating the bonding agent holdingmember to move the point of contact between the bonding agent and thebarrier rib tops along the length of the barrier ribs.
 7. The displaypanel manufacturing method of any one of claims 1 to 5, wherein thebonding agent applying process is repeated a plurality of times for asame substrate.
 8. The display panel manufacturing method of claim 6,wherein the bonding agent applying process is repeated a plurality oftimes for a same substrate.
 9. The display panel manufacturing method ofone of claims 4 and 5, wherein the bonding agent is held by theregulating means.
 10. The display panel manufacturing method of claim 6,wherein the bonding agent is held by the regulating means.
 11. Thedisplay panel manufacturing method of any one of claims 2 to 5, whereinthe bonding agent is formed in a layer on a flat plate.
 12. The displaypanel manufacturing method of claim 4, wherein the regulating means isformed from interwoven wire rods.
 13. The display panel manufacturingmethod of claim 4, wherein the regulating means is indentations andprotrusions formed on a surface of a bonding agent holding member. 14.The display panel manufacturing method of claim 4, wherein theregulating means is a plurality of half-cylinders, and the barrier ribtops are brought into contact with the curved surface of thehalf-cylinders.
 15. The display panel manufacturing method of any one ofclaims 1 to 5, claims 8, and 10, and claims 12 to 14, further includinga process for leveling the barrier ribs across almost the entire surfaceof the substrate so that all the barrier rib tops are at approximatelythe same height.
 16. The display panel manufacturing method of claim 6,including a process for leveling the barrier ribs across almost theentire surface of the substrate so that all the barrier rib tops are atapproximately the same height.
 17. The display panel manufacturingmethod of claim 7, including a process for leveling the barrier ribsacross almost the entire surface of the substrate so that all thebarrier ribs are at approximately the same height.
 18. The display panelmanufacturing method of claim 9, including a process for leveling thebarrier ribs across almost the entire surface of the substrate so thatall the barrier ribs are at approximately the same height.
 19. Thedisplay panel manufacturing method of claim 11, including a process forleveling the barrier ribs across almost the entire surface of thesubstrate so that all the barrier ribs are at approximately the sameheight.
 20. A display panel manufacturing method, for connecting a pairof substrates arranged in opposition via (1) a plurality of barrier ribsformed in a specific pattern on at least one of the substrates and (2) abonding agent arranged on the barrier ribs, the display panelmanufacturing method comprising a barrier rib pattern forming processand a bonding agent pattern forming process, including: a first step forlaminating the bonding agent and a material for forming the barrier ribsby forming layers of certain thicknesses; a second step forsimultaneously removing corresponding parts of the laminated barrier ribmaterial and bonding agent to form the specific pattern; and a thirdstep for transferring the pattern formed in the barrier rib formingmaterial and bonding agent to the substrate on which the barrier ribsare to be formed.
 21. A display panel manufacturing method, forconnecting a pair of substrates arranged in opposition, via a bondingagent, which has been applied to a plurality of barrier ribs formed in aspecific pattern on at least one of the substrates, the display panelmanufacturing method comprising: a barrier rib pattern forming processfor forming a barrier rib pattern by pressing a first pattern-formingmember onto the barrier rib forming material, the barrier rib formingmaterial being of a set thickness, and a bonding agent pattern formingprocess using a pattern-forming member having the same pattern as thepattern-forming member used in the barrier rib pattern forming process.22. The display panel manufacturing method of claim 21, wherein thebarrier rib pattern forming process and the bonding agent patternforming process include: a first step for laminating the barrier ribforming material and the bonding agent by forming layers of certainthicknesses; a second step for simultaneously pressing down thelaminated barrier rib forming material and bonding agent using a samepattern-forming member to form the specific pattern; and a third stepfor transferring a molded pattern formed in the barrier rib formingmaterial and bonding agent to the substrate on which the barrier ribsare to be formed.
 23. A display panel manufacturing method, wherein atleast one indentation and protrusion is formed on the parts of thepattern-forming member used in claim 21 that correspond to top surfacesof the barrier ribs on which the bonding agent is applied.
 24. A displaypanel manufacturing method, for connecting a pair of substrates arrangedin opposition via a bonding agent arranged on a plurality of barrierribs formed in a specific pattern on at least one of the substrates, thedisplay panel manufacturing method comprising: an indentation formingprocess for forming at least one indentation on a top of each barrierrib; and a bonding agent arranging process for arranging the bondingagent in the indentations.
 25. The display panel manufacturing method ofclaim 24, the barrier rib pattern being formed by pressing apattern-forming member onto the barrier rib forming material, thebarrier rib forming material being arranged in a layer of a specificthickness, and the indentation forming process is performedsimultaneously with the barrier rib pattern formation when thepattern-forming member is pressed onto the barrier rib forming material.26. The display panel manufacturing process of one of claims 24 and 25,wherein the bonding agent arranging process is performed by injectingthe bonding agent into the indentations using a nozzle.
 27. A displaypanel manufacturing method, for connecting a pair of substrates arrangedin opposition via a bonding agent arranged on a plurality of barrierribs formed in a specific pattern on at least one of the substrates,wherein a process for arranging the bonding agent on the barrier ribsincludes: an attaching process for attaching a first member to thebarrier ribs; a first removing process for forming holes in the firstmember at positions corresponding to tops of the barrier ribs; a bondingagent filling process for filling the holes in the first member with thebonding agent; and a second removing process for removing the remainingfirst member.
 28. The display panel manufacturing method of claim 27,wherein the adhesion process is performed by applying the first memberto the barrier ribs after a connecting layer is formed on either thebarrier ribs or the first member.
 29. The display panel manufacturingmethod of one of claims 27 and 28, wherein the first removing processforms holes by irradiating the surface of the first member with a laser.30. The display panel manufacturing method of claim 29, wherein thelaser irradiation is controlled according to measurements taken tolocate the barrier ribs.
 31. The display panel manufacturing method ofclaim 29, wherein a material used for the barrier rib tops absorbs laserlight more easily than a material used for other parts of the barrierribs.
 32. The display panel manufacturing method of claim 30, wherein amaterial used for the barrier rib tops absorbs laser light more easilythan a material used for other parts of the barrier ribs.
 33. Thedisplay panel manufacturing method of one of claims 27 and 28, wherein aphotoresist is used as the first member; and the first removing processforms holes by irradiating the first member in a specific pattern andthen developing the first member.
 34. The display panel manufacturingmethod of one of claims 27 and 28, wherein the first removing processforms holes in the first member adhering to the barrier rib tops using agrinding method.
 35. The display panel manufacturing method of one ofclaims 27 to 34, wherein the second removing process removes theremainder of the first member using one of peeling, melting andsublimation.
 36. A display panel manufacturing method, for connecting apair of substrates arranged in opposition via a bonding agent applied toa plurality of barrier ribs formed on at least one of the substrates,wherein a process for arranging the bonding agent on the barrier ribsincludes: an arranging process for bringing a bond sheet, made byforming a sheet of bonding agent in advance, into contact with tops ofthe barrier ribs; a transfer process for transferring the bonding agentto the parts of the barrier rib in contact with the bond sheet; and aremoving process for separating the bond sheet from the barrier ribs.37. The display panel manufacturing method of claim 36, wherein thetransfer process transfers the bonding agent to the parts of the barrierrib tops in contact with the bond sheet by pressing the bonding agentsheet onto the barrier rib tops.
 38. The display panel manufacturingmethod of claim 37, wherein the transfer process heats the parts of thebond sheet in contact with the barrier rib tops.
 39. A display panelmanufacturing method, for connecting a pair of substrates arranged inopposition via a plurality of barrier ribs formed on at least one of thesubstrates, and a bonding agent applied to the barrier ribs, the displaypanel manufacturing method comprising: a applying process for applyingthe bonding agent to an area on each barrier rib that is at least aslarge as a top of each barrier rib; a hardening process for hardeningparts of the attached bonding agent; and a removing process for removingthe parts of the bonding agent that have not been hardened.
 40. Thedisplay panel manufacturing method of claim 39, wherein, in the applyingprocess, a compound of bonding agent and photo-hardening resin isapplied to the barrier rib tops; and in the hardening process, parts ofthe applied compound are exposed to light, causing the exposed parts ofthe compound to harden.
 41. The display panel manufacturing method ofclaim 40, wherein a resin that hardens upon exposure to ultra-violetlight is used as the photo-hardening resin, and the light used in thehardening process is ultra-violet light.
 42. The display panelmanufacturing method of claim 41, wherein, in the hardening process,after ultra-violet irradiation has taken place, hardened parts of thebonding agent are heated.
 43. The display panel manufacturing method ofany one of claims 1, 20, 21, 24, 27, 36 and 39, wherein the bondingagent is arranged on the barrier ribs using a compound including a firstsubstance which is more difficult to melt than the bonding agent.
 44. Agas discharge panel, including a first substrate, on which a pluralityof pairs of electrodes extending in a first direction, and a dielectriclayer covering the electrodes have been formed, and a second substrate,on which a plurality of barrier ribs, extending in a second directiondiffering from the first direction, are formed in opposition to thedielectric layer and the electrode pairs so that the barrier ribs areseparated from the dielectric layer and the electrode pairs, wherein thedielectric layer and the barrier ribs are at least partially connected;and the panel is structured such that discharge mainly occurs in partsof the panel separated from the positions where the barrier ribs and thedielectric layer are connected.
 45. The gas discharge panel of claim 44,wherein a space between electrodes in each electrode pair has wide andnarrow parts; and the narrow parts are located in gaps between parts ofthe dielectric layer where adjacent barrier ribs are connected.
 46. Thegas discharge panel of claim 44, wherein the parts of the dielectriclayer to which the barrier ribs are not connected are covered with aprotective film.
 47. The gas discharge panel of claim 44, wherein theparts of the dielectric layer connected to the barrier ribs are thickerthan the other parts of the dielectric layer.
 48. The gas dischargepanel of claim 44, wherein a protective film is formed on the surface ofthe dielectric layer, and the protective film and the barrier ribs areconnected; and the surface roughness of the parts of the protectivelayer to which the barrier ribs are connected is less than the surfaceroughness of other parts of the protective layer.
 49. The gas dischargepanel of claim 44, wherein a protective film is formed on the surface ofthe dielectric layer, and the protective film and the barrier ribs areconnected; and the parts of the protective layer to which the barrierribs are connected are thicker than the other parts of the protectivelayer.
 50. The gas discharge panel of claim 44, wherein the parts of thebarrier ribs that do not correspond to cells are connected to the firstsubstrate.
 51. The gas discharge panel of claim 44, wherein the barrierribs are at least partially connected to the first substrate by abonding agent applied to the barrier rib tops so as to cover an areanarrower than each barrier rib top.
 52. The gas discharge panel of anyone of claims 44 to 51, wherein gas is enclosed at a pressure of no lessthan 760 torr in a space between the first and second substrates.
 53. Adisplay panel, formed from a pair of substrates arranged in oppositionand connected via a bonding agent applied to a plurality of barrier ribsformed on at least one of the substrates, the bonding agent beingapplied to at least part of each barrier rib; wherein a substance havingone of a different melting point and softening point from a substanceused for the part of the substrate connected to the bonding agent isused for the bonding agent; and the pair of substrates are connectednear top parts of each barrier rib.
 54. The display panel of claim 53,wherein one of the melting and softening point of the bonding agent ishigher than one of a melting and softening point of the parts of thepair of substrates connected to the bonding agent.
 55. The display panelof claim 53, wherein one of the melting and softening point of thebonding agent is lower than one of a melting and softening point of theparts of the pair of substrates connected to the bonding agent.
 56. Thedisplay panel of any one of claims 53 to 55, wherein most of an areanear the top parts of the barrier ribs is connected to a substrate. 57.The display panel of any one of claims 53 to 55, wherein the displaypanel is a gas discharge panel in which gas is enclosed between the pairof substrates, and the pressure at which the-gas is enclosed is set atno less than 760 torr.
 58. The display panel of claim 56, wherein thedisplay panel is a gas discharge panel in which gas is enclosed betweenthe pair of substrates, and the pressure at which the gas is enclosed isset at no less than 760 torr.
 59. A display panel, formed from a pair ofsubstrates arranged in opposition and connected via a bonding agentapplied to a plurality of barrier ribs formed on at least one of thesubstrates, the bonding agent being applied to at least part of eachbarrier rib, wherein the bonding agent includes a first substance whichis more difficult to melt than the bonding agent.